Beef Wellingtons Recipes

CLASSIC BEEF WELLINGTONS

Steps:

• Sprinkle steaks with 1/2 teaspoon salt and 1/4 teaspoon pepper. In a large skillet, brown steaks in 1 tablespoon oil for 2-3 minutes on each side. Remove from skillet and refrigerate until chilled., In the same skillet, saute mushrooms and onion in remaining oil until tender. Stir in remaining salt and pepper; cool to room temperature., Preheat oven to 425°. On a lightly floured surface, roll each puff pastry sheet into a 14x9-1/2-in. rectangle. Cut into two 7-in. squares (use scraps to make decorative cutouts if desired). Place a steak in the center of each square; top with mushroom mixture. Lightly brush pastry edges with water. Bring opposite corners of pastry over steak; pinch seams to seal tightly., Place in a greased 15x10x1-in. baking pan. Cut four small slits in top of pastry. Arrange cutouts over top if desired. Brush with egg., Bake 25-30 minutes or until pastry is golden brown and meat reaches desired doneness (for medium-rare, a thermometer should read 135°; medium, 140°; medium-well, 145°).

THE ULTIMATE BEEF WELLINGTON

Steps:

• For the Duxelles:
• To make the Duxelles: Add mushrooms, shallots, garlic, and thyme to a food processor and pulse until finely chopped. Add butter and olive oil to a large saute pan and set over medium heat. Add the shallot and mushroom mixture and saute for 8 to 10 minutes until most of the liquid has evaporated. Season with salt and pepper and set aside to cool.
• For the Beef:
• To prepare the beef: Tie the tenderloin in 4 places so it holds its cylindrical shape while cooking. Drizzle with olive oil, then season with salt and pepper and sear all over, including the ends, in a hot, heavy-based skillet lightly coated with olive oil - about 2 to 3 minutes. Meanwhile set out your prosciutto on a sheet of plastic wrap (plastic needs to be about a foot and a half in length so you can wrap and tie the roast up in it) on top of your cutting board. Shingle the prosciutto so it forms a rectangle that is big enough to encompass the entire filet of beef. Using a rubber spatula cover evenly with a thin layer of duxelles. Season the surface of the duxelles with salt and pepper and sprinkle with fresh thyme leaves. When the beef is seared, remove from heat, cut off twine and smear lightly all over with Dijon mustard. Allow to cool slightly, then roll up in the duxelles covered prosciutto using the plastic wrap to tie it up nice and tight. Tuck in the ends of the prosciutto as you roll to completely encompass the beef. Roll it up tightly in plastic wrap and twist the ends to seal it completely and hold it in a nice log shape. Set in the refrigerator for 30 minutes to ensure it maintains its shape.
• Preheat oven to 425 degrees F.
• On a lightly floured surface, roll the puff pastry out to about a 1/4-inch thickness. Depending on the size of your sheets you may have to overlap 2 sheets and press them together. Remove beef from refrigerator and cut off plastic. Set the beef in the center of the pastry and fold over the longer sides, brushing with egg wash to seal. Trim ends if necessary then brush with egg wash and fold over to completely seal the beef - saving ends to use as a decoration on top if desired. Top with coarse sea salt. Place the beef seam side down on a baking sheet.
• Brush the top of the pastry with egg wash then make a couple of slits in the top of the pastry using the tip of a paring knife ¿ this creates vents that will allow the steam to escape when cooking. Bake for 40 to 45 minutes until pastry is golden brown and beef registers 125 degrees F on an instant-read thermometer. Remove from oven and rest before cutting into thick slices. Garnish with minced chives, and serve with Green Peppercorn Sauce, Roasted Fingerling Potatoes with Fresh Herbs and Garlic, and Warm Wilted Winter Greens.
• Add olive oil to pan after removing beef. Add shallots, garlic, and thyme; saute for 1 to 2 minutes, then, off heat, add brandy and flambe using a long kitchen match. After flame dies down, return to the heat, add stock and reduce by about half. Strain out solids, then add 2 cups cream and mustard. Reduce by half again, then shut off heat and add green peppercorns.
• Preheat oven to 500 degrees F and place a baking sheet inside to heat.
• Add potatoes, rosemary, sage, thyme, and garlic to a medium bowl. Drizzle with olive oil, and season with salt and pepper. Remove sheet pan from oven, lightly coat with olive oil, and pour potatoes onto pan. Place potatoes in oven and reduce heat to 425 degrees F. Roast for 20 minutes, or until crispy on outside and tender on inside.
• Cook honey and balsamic together over medium-high heat in a large saute pan, about 5 minutes. Toast walnuts in a small skillet; set aside to cool.
• Pile greens on a platter. Stir mustard into balsamic-honey dressing, then whisk in about 1 cup extra-virgin olive oil; pour over greens. Season greens with salt and pepper and garnish with walnuts, pomegranate seeds, shavings of Parmesan, and shallot.

BEEF WELLINGTON

Steps:

• Preheat oven to 425 degrees F (220 degrees C). Place beef in a small baking dish, and spread with 2 tablespoons softened butter. Bake for 10 to 15 minutes, or until browned. Remove from pan, and allow to cool completely. Reserve pan juices.
• Melt 2 tablespoons butter in a skillet over medium heat. Saute onion and mushrooms in butter for 5 minutes. Remove from heat, and let cool.
• Mix together pate and 2 tablespoons softened butter, and season with salt and pepper. Spread pate over beef. Top with onion and mushroom mixture.
• Roll out the puff pastry dough, and place beef in the center. Fold up, and seal all the edges, making sure the seams are not too thick. Place beef in a 9x13 inch baking dish, cut a few slits in the top of the dough, and brush with egg yolk.
• Bake at 450 degrees F (230 degrees C) for 10 minutes, then reduce heat to 425 degrees F (220 degrees C) for 10 to 15 more minutes, or until pastry is a rich, golden brown. Set aside, and keep warm.
• Place all reserved juices in a small saucepan over high heat. Stir in beef stock and red wine; boil for 10 to 15 minutes, or until slightly reduced. Strain, and serve with beef.

BEEF WELLINGTONS (COOKING FOR 2)

Steps:

• Season steaks with salt and pepper. In 10-inch skillet, heat oil over high heat. Add steaks; cook 2 minutes on each side to brown. Remove steaks; refrigerate 30 minutes.
• Meanwhile, melt 2 tablespoons butter in same skillet over medium-high heat. Add 2 tablespoons shallot and 1 clove garlic; cook and stir about 2 minutes or until softened. Add mushrooms, prosciutto and thyme; cook and stir 3 to 4 minutes or until mushrooms have softened and any liquid has evaporated. Transfer mushroom mixture to bowl; refrigerate 10 to 15 minutes or until completely cooled.
• Line large rimmed cookie sheet with cooking parchment paper. Roll puff pastry sheet to 20x9 inches; using sharp knife, cut out two 9-inch rounds. From scraps, cut out leaves or other shapes to use as decoration. Place pastry rounds and decorative cutouts on cookie sheet. Place in freezer 5 minutes.
• Heat oven to 400°F. In small bowl, beat egg and water.
• Remove pastry from freezer; brush each round with 1 teaspoon mustard. Place generous tablespoon of the mushroom mixture in center of each pastry. Place a steak on top of mushroom mixture on each pastry round; top each steak with another generous tablespoon mushroom mixture. Brush edges of each pastry round with egg wash; fold pastry over steak so dough edges slightly overlap and steaks are completely enclosed. Place on cookie sheet, seam side down; brush top and sides with egg wash. Place decorative cutouts on top of each; brush cutouts with more egg wash. Place in freezer 5 minutes.
• Remove from freezer; bake 20 to 25 minutes or until pastry is golden brown and meat thermometer inserted in thickest part of beef reads 135°F for medium-rare (temperature will continue to rise to 145°F while it stands). Place on rack; let stand 10 minutes.
• Meanwhile, in 10-inch skillet, heat 1 tablespoon butter over medium heat. Add 2 tablespoons shallot and 1 clove garlic; cook and stir 1 to 3 minutes or until softened. Stir in 1 teaspoon mustard. Remove from heat; add broth, whipping cream and brandy. Heat to boiling over medium-high heat. Reduce heat; cook 6 to 8 minutes, stirring occasionally, until slightly thickened. Stir in parsley. Serve sauce with Wellingtons.

INDIVIDUAL BEEF WELLINGTONS

Steps:

• In a large skillet over medium heat, combine the mushrooms, onion, sherry, butter or margarine and parsley and saute until all the liquid is absorbed and the mixture resembles a paste. Cover the top of each steak with the mixture.
• Partially thaw the puff pastry sheets and roll out pieces thin enough to cover the top, sides and bottom of each steak. Place the steaks on a baking sheet, cover with plastic wrap and store in the refrigerator until serving time.
• Preheat oven to 425 degrees F (220 degrees C).
• Bake steaks uncovered in the preheated oven for 25 minutes. (Note: They will be rare but will continue cooking while dish is sitting.)

BEEF WELLINGTON FOR TWO RECIPE BY TASTY

Steps:

• In a food processor, place mushrooms, garlic, salt, pepper, and thyme and blend into a fine paste (about 30-60 seconds).
• Transfer to a medium-sized frying pan, being sure to spread it evenly across the bottom of the pan.
• Cook the mushrooms over medium-low heat while stirring frequently. After about 7-10 minutes the mushroom mixture should shrink to half the original volume and begin to form a paste.
• NOTE: The goal here is to cook off the bulk of the water inside the mushrooms. This'll keep the puff pastry from being too mushy at the end.
• At this point, remove the mushroom mixture from the heat and set it aside.
• Preheat oven to 400˚F (200˚C).
• Liberally season the outside of the tenderloin pieces with salt and pepper.
• In another medium-sized frying pan, heat 2 tablespoons of neutral oil over high heat. Once the oil has begun to smoke, quickly sear the tenderloin pieces on both sides (45-60 seconds per-side).
• Once seared, transfer the meat to a plate or cutting board to rest.
• Using a basting brush, generously paint the mustard over the resting pieces of beef, making sure to coat both sides.
• To assemble the Wellingtons, lay out a piece of puff pastry on a lightly floured surface. Place a piece of ham in the center of the pasty.
• Next, layer about 1 tablespoon of the mushroom mixture on the center of the ham using the back of a spoon to flatten the paste to about the size of the tenderloin pieces.
• Place one of the mustard-coated beef fillet on top of the mushroom mixture, then top the piece of beef with another spoonful of the mushroom mixture, making sure to pat it down flat across the top of the meat.
• Layer with another piece of ham and close the the Wellington by folding the puff pastry over the center of the meat.
• Using your hands, carefully seal the edges of the pastry then transfer SEAM-SIDE DOWN to a baking tray lined with parchment paper.
• Lightly brush the outside of each Wellington with egg wash.
• Using the back of a paring knife, lightly score the tops of the pasty in a checkered pattern, being careful not to pierce the pastry.
• Bake the Wellingtons in a 400˚F (200˚C) oven until the pastry is fully cooked and golden brown (about 20 minutes).
• Allow each Wellington to rest at least 10 minutes before cutting into it.
• Enjoy!

GROUND BEEF WELLINGTON

Steps:

• In a saucepan, saute mushrooms in butter until softened. Stir in flour and 1/8 teaspoon pepper until blended. Gradually add the cream. Bring to a boil; cook and stir until thickened, about 2 minutes. Remove from the heat and set aside., In a bowl, combine the egg yolk, onion, 2 tablespoons mushroom sauce, salt and remaining 1/8 teaspoon pepper. Crumble beef over mixture and mix well. Shape into 2 loaves. Separate crescent dough into 2 rectangles on a baking sheet. Seal perforations. Place a meat loaf on each rectangle. Bring dough edges together and pinch to seal. If desired, brush with egg wash. Bake at 350° until golden brown and a thermometer inserted into meat loaf reads 160°, 24-28 minutes., Meanwhile, warm remaining sauce over low heat; stir in parsley. Serve sauce with Wellingtons.

SHOW-STOPPING BEEF WELLINGTON RECIPE BY TASTY

Steps:

• Let the beef tenderloin come to room temperature. Season with kosher salt and pepper on all sides.
• Add canola oil to a large pan on high heat. Once the oil is hot, add the tenderloin. Without moving the tenderloin, cook until a dark brown crust forms, about 3 minutes per side. Repeat searing on all sides, including the tenderloin ends.
• Remove the tenderloin from the pan and transfer to a cutting board or wire rack and remove ties.
• Brush the mustard on all sides of the meat while it's still warm. Let the meat rest for while making the duxelle (mushrooms cooked and reduced until dry).
• To the same pan, add the butter, mushrooms, minced shallot, and minced garlic over medium-high heat. Cook, stirring occasionally, until all the liquid evaporates and the mushroom mixture becomes a thick 25-30 minutes, dry-like paste. Season with salt and pepper to taste.
• Remove the mushrooms from the pan and let cool completely.
• Place a large layer of overlapping sheets of plastic wrap on your work surface that is twice the length and width of the tenderloin.
• Lay overlapping strips of prosciutto on the plastic into an even square layer.
• Spread a layer of the mushrooms evenly over the prosciutto.
• Tightly and evenly wrap the tenderloin with the prosciutto, using the plastic wrap to wrap it even tighter and seal ends. Tie the ends of the plastic wrap together to hold the Wellington's shape. Place in the refrigerator for 15 minutes.
• Preheat oven to 400°F (200°C).
• Place a new layer of plastic wrap on the work surface and lay a sheet of puff pastry over it. Unwrap the prosciutto-wrapped beef tenderloin onto the puff pastry, wrapping until the ends meet. Cut off any extra puff pastry, making sure there is no overlap.
• Wrap the puff pastry in plastic wrap, tying the ends together to form a log shape. Place in the refrigerator for 15 minutes.
• Place the beef Wellington on a greased, parchment paper-lined baking sheet. Brush the surface with the beaten eggs. With a fork, score a decorative design onto the surface of the puff pastry.
• Decorate with additional pastry (optional). Sprinkle with kosher salt.
• Bake for 40 minutes or until the puff pastry is a dark golden brown and the internal temperature of the beef is 135°F (57°C) for medium-rare.
• Enjoy!

INDIVIDUAL BEEF WELLINGTONS

Steps:

• Heat a large skillet over medium-high and add 1 tablespoon oil. Generously season the filets mignons with salt and pepper, and sear until the surfaces on the top, bottom and rounded sides are no longer raw, about 2 minutes total. Transfer the steaks to a plate, reserving the oil in the skillet. Brush or spread the Dijon mustard all over each filet mignon and refrigerate until cool, about 15 minutes.
• Turn the heat to medium-high, and add the remaining 1 tablespoon oil to the skillet. Add the mushrooms and shallot, season with salt and pepper, and cook, stirring occasionally, until deeply browned and no longer watery, 10 to 12 minutes. Be patient: The mushrooms will first release some water; then, once that liquid evaporates, the vegetables will start to brown. If the vegetables are sticking before they can brown, lower the heat or add a little water to the pan.
• When the mushrooms are deeply browned, reduce the heat to medium and stir in the herbes de Provence, honey, wine and cream. Let the liquids bubble up and reduce until the mixture is thick and jammy, about 2 minutes. Transfer to a small dish and refrigerate until cool.
• To assemble the Wellingtons, cut the puff pastry sheet in half (it doesn't matter which direction). Use a rolling pin or empty wine bottle to evenly roll each sheet into an 1/8-inch-thick rectangle. Mount a filet mignon-size circle of the chilled mushroom mixture in the center of each rolled-out sheet, evenly dividing the mixture between the two pastry pieces. Top each mound of mushrooms with a filet mignon.
• Carefully bring the edges of the puff pastry up and over the steaks, stretching the dough if needed to completely cover the meat. Twist the tops of the dough to seal the filling, as if you're making dumplings. You want an even, uniform layer of pastry, so trim any overlapping dough as you go. When the tops are nicely sealed, flip the Wellingtons over, seam side down, and transfer to a parchment-lined sheet pan. You can use your hands to gently tighten each Wellington into perfectly smooth spheres. Refrigerate to chill completely before baking, at least 30 minutes or up to 24 hours.
• Heat the oven to 425 degrees. In a small dish, whisk the egg until homogenous and, using a pastry brush or your fingers, evenly coat the entire outsides of the chilled Wellingtons with the egg. Bake until the pastry is golden brown, 17 to 20 minutes. The internal temperature of the steak should read 120 degrees for medium-rare (it will continue to cook as it rests).
• Transfer the Wellingtons to serving plates. Let them rest for about 15 minutes before serving.

BEEF WELLINGTON

Steps:

• Preheat the oven to 400˚F. Line a baking sheet with parchment paper, and set it aside. Place a wire baking rack on a sheet pan and set aside.
• Heat a large cast-iron skillet over high heat. Season the meat with salt and pepper to taste. When the pan is hot, add the cooking spray. Add the meat. Sear, turning it occasionally, until the meat is a deep golden brown all over, about 4 minutes total.
• While the meat is searing, pulse the mushrooms, in two batches, in a food processor until they are very finely chopped.
• Remove the skillet from the heat, and transfer the meat to the wire baking rack set over the sheet pan. Spray the skillet with cooking spray and place it over medium-low heat. Add the shallots and about half of the thyme. Cook, stirring occasionally, until the shallots start to become tender and fragrant, about 2 minutes.
• Raise the heat to high. Add the mushrooms to the skillet. Sauté, stirring occasionally, until the mushrooms have released their liquid and the liquid has mostly evaporated, about 10 minutes. Add the sherry and cook for another minute. Add the pâté and stir until it is fully incorporated into the mushrooms. Season the mixture with salt and pepper to taste. Let it cool slightly.
• On a work surface, lay down 1 sheet of phyllo. Spray the phyllo lightly and evenly with cooking spray. Sprinkle it with one quarter of the remaining thyme. Repeat the process with the remaining 3 sheets of phyllo, stacking the sheets as you go.
• Working with the shorter side of the phyllo toward you, spread the mushroom mixture over the lower half half of the phyllo, leaving a 1-inch border on the sides. Place the beef on top of the mushroom mixture. Fold up the sides of the phyllo on the right and left of the beef to encase it. Roll up the beef in the phyllo.
• Place the beef-phyllo package, seam side down, on the prepared baking sheet. Spray the package lightly with cooking spray. Season it with salt and pepper.
• Roast until the meat is medium-rare, about 20 minutes. Let the Beef Wellington rest for 5 minutes before slicing.
• Phyllo dough is low in fat and contains no saturated fat or trans fats, and no cholesterol. It's light and flaky, and as long as you use butter-flavored cooking spray and/or olive oil cooking spray between layers rather than real melted butter or olive oil it's a perfect low-fat/low-calorie swap for most recipes that call for dough of any kind.
• Fat: 91.3g (before), 11.7g (after)
• Calories: 1,156 (before), 335 (after)
• Protein: 38g
• Carbohydrates: 17g
• Cholesterol: 123mg
• Fiber: 2g
• Sodium: 352mg

BEEF WELLINGTON

Steps:

• Tie tenderloin with kitchen twine in 1-inch increments to form an even piece, so it will hold its shape during cooking. (Your butcher can do this for you.)
• Heat a large cast-iron or heavy skillet over medium-high heat. Season beef with 1 teaspoon salt and 1/4 teaspoon pepper. Sear tenderloin until well browned on all surfaces, about 1 1/2 minutes on each side, including ends.
• Transfer tenderloin to a cutting board with a drainage well; let rest until cool. Cut and remove the kitchen twine, and chill tenderloin until ready to assemble and beef is cold, at least 1 hour or overnight.
• In another large skillet, heat butter over medium heat. Add onion; cook until it softens, about 4 minutes. Add mushrooms; season with remaining teaspoon salt and 1/4 teaspoon pepper. Cook, stirring occasionally, until they are tender and liquid is released and evaporates, 8 to 10 minutes. Add sherry; cook until mixture is dry, about 4 minutes more. Cool at room temperature or in the refrigerator for up to a day.
• On a lightly floured surface, roll the puff pastry into a rectangle 1/4 inch thick and big enough to enclose the beef. If using store-bought pastry, it may be necessary to lay out 2 pieces, overlapping, and roll them out into one piece. Spread the top of the tenderloin evenly with half the mousse, and spread half of the mushrooms evenly over the top.
• Carefully invert coated tenderloin into middle of puff pastry, mushroom-side down. Spread another layer of mousse on top and sides of tenderloin. Spread remaining mushrooms over top. Fold up long sides of dough to enclose tenderloin, brushing edges with beaten egg to seal. Trim ends if necessary, then fold up, and seal. Carefully transfer tenderloin, seam side down, to a baking sheet, and chill at least 2 hours or overnight. Roll out any extra dough, cut into holly or other shapes if desired, and chill on baking sheet with beef.
• Preheat the oven to 425 degrees. Place a baking sheet on the middle rack in the oven until hot, about 15 minutes. Decorate top of pastry with shaped cutouts if desired; brush with beaten egg. Make 2 to 3 slits in pastry for venting steam. Sprinkle with sea or coarse salt if desired. Carefully transfer beef Wellington to preheated baking sheet. Bake until pastry is golden brown and beef registers 120 degrees to 130 degrees on an instant-read thermometer for rare, 130 degrees to 135 degrees for medium rare, 35 to 50 minutes. Cover pastry with foil if it gets too brown while cooking. Let rest on a cutting board 10 minutes before slicing.

BEEF WELLINGTON

Steps:

• Heat oven to 220C/fan 200C/gas 7.
• Sit the 1kg beef fillet on a roasting tray, brush with 1 tbsp olive oil and season with pepper, then roast for 15 mins for medium-rare or 20 mins for medium. When the beef is cooked to your liking, remove from the oven to cool, then chill in the fridge for about 20 mins.
• While the beef is cooling, chop 250g chestnut (and wild, if you like) mushrooms as finely as possible so they have the texture of coarse breadcrumbs. You can use a food processor to do this, but make sure you pulse-chop the mushrooms so they don't become a slurry.
• Heat 2 tbsp of the olive oil and 50g butter in a large pan and fry the mushrooms on a medium heat, with 1 large sprig fresh thyme, for about 10 mins stirring often, until you have a softened mixture.
• Season the mushroom mixture, pour over 100ml dry white wine and cook for about 10 mins until all the wine has been absorbed. The mixture should hold its shape when stirred.
• Remove the mushroom duxelle from the pan to cool and discard the thyme.
• Overlap two pieces of cling film over a large chopping board. Lay 12 slices prosciutto on the cling film, slightly overlapping, in a double row.
• Spread half the duxelles over the prosciutto, then sit the fillet on it and spread the remaining duxelles over.
• Use the cling film's edges to draw the prosciutto around the fillet, then roll it into a sausage shape, twisting the ends of cling film to tighten it as you go.
• Chill the fillet while you roll out the pastry.
• Dust your work surface with a little flour. Roll out a third of the 500g pack of puff pastry to a 18 x 30cm strip and place on a non-stick baking sheet.
• Roll out the remainder of the 500g pack of puff pastry to about 28 x 36cm.
• Unravel the fillet from the cling film and sit it in the centre of the smaller strip of pastry.
• Beat the 2 egg yolks with 1 tsp water and brush the pastry's edges, and the top and sides of the wrapped fillet.
• Using a rolling pin, carefully lift and drape the larger piece of pastry over the fillet, pressing well into the sides.
• Trim the joins to about a 4cm rim. Seal the rim with the edge of a fork or spoon handle.
• Glaze all over with more egg yolk and, using the back of a knife, mark the beef Wellington with long diagonal lines taking care not to cut into the pastry.
• Chill for at least 30 mins and up to 24 hrs. Heat oven to 200C/fan 180C/gas 6.
• Brush the Wellington with a little more egg yolk and cook until golden and crisp - 20-25 mins for medium-rare beef, 30 mins for medium. Allow to stand for 10 mins before serving in thick slices.

BEEF WELLINGTON

Steps:

• Using kitchen twine, tie the tenderloin into a 12-inch log, folding the thinner end onto itself. (Use your hands to squeeze the meat into a log. You can be aggressive here.)
• Place pancetta in a cold 12-inch skillet. Cook over medium heat, stirring occasionally, until pancetta starts to brown, 6 to 8 minutes.
• Add butter, raise heat to high, and stir in mushrooms and shallot. Cook until the liquid released by the mushrooms has cooked off, 4 to 7 minutes. Reduce heat to medium and continue to cook until mushrooms are browned, stirring frequently, another 18 to 23 minutes. (Take your time here, you want a deep golden color for the best flavor.) Scrape bottom of the skillet as necessary to prevent burning.
• If the pan looks dry, drizzle in a little olive oil, then stir in garlic and thyme leaves. Cook until fragrant, another 1 to 2 minutes. Stir in sherry, scraping up the browned bits on the bottom of the pan. Scrape mixture into a medium bowl to cool. (Do not add salt at this point.)
• In the same skillet, heat 2 tablespoons olive oil over medium-high. Season beef generously with salt and pepper, then sear on all sides until browned, 1 to 2 minutes per side. Transfer to a plate, and cool slightly. Remove any twine. Brush meat all over with mustard.
• On a clean work surface, overlap long sheets of plastic wrap (about 15-by-15 inches). Place prosciutto slices on top to make about a 14-by-7-inch rectangle, arranging them in an even layer and overlapping the pieces slightly. Spread cooled mushroom mixture on top.
• Place beef along one long end of the prosciutto slices, and roll prosciutto tightly around beef. Wrap tightly with plastic wrap, twisting both ends like a candy wrapper. Chill in the refrigerator for at least 30 minutes and up to overnight.
• Meanwhile, heat oven to 400 degrees, and line a rimmed baking sheet with parchment paper. In a small bowl, whisk together egg and 1 teaspoon water. Lay puff pastry out on the prepared baking sheet, lightly draping over edges. (The pastry needs to be at least 14-inches long and 13-inches wide to cover the beef; if not, roll it out as needed.)
• Carefully unwrap and place chilled log along the edge of one long side of puff pastry. Roll beef up tightly, then place it seam-side down on the baking sheet. Tuck puff pastry over the ends of the beef to cover them, pinching to seal and folding underneath. Brush top and sides of pastry with egg wash, and use a small sharp knife to cut a few slits into the top of the pastry.
• Bake until a thermometer inserted in the center reads 115 degrees for rare, 25 to 35 minutes. (This timing will yield rare pieces at the thicker end and medium done pieces at the thinner end of the loin.) Remove from oven and let rest for 10 minutes, then slice and serve while warm.