Puff Pastry

1. Defrost puff pastry on a baking sheet lined with parchment paper. Preheat oven to 400F.

Mushroom Duxelle

1. Add mushrooms, garlic, and onion to food processor and pulse until the mushroom mixture resembles coarse breadcrumbs. Do not over pulse.
2. In a pan over medium heat add oil and butter. Add mushroom mixture, salt, pepper and thyme sprig. Sauté until all moisture has evaporated; mixture must be dry and cooled. Remove sprig of thyme.

Beef

1. Dry round tenderloin steaks and lightly season with salt and pepper. In a skillet over medium high heat add oil and butter. Sear all sides of each tenderloin, including sides. Remove from heat, evenly brush mustard on both steaks and allow to rest.

Assembly

1. Line a cooking surface with plastic wrap, lay 4 slices of prosciutto on film, slightly overlapping each piece.
2. Spread half of the Duxelle over the prosciutto.
3. Place beef on top of the prosciutto layered with Duxelle.
4. Using the plastic wrap lift the edges to wrap the prosciutto around the beef tenderloin filet.
5. Once all sides are covered use the plastic wrap to tighten the tenderloin package and twist at the end to tighten and shape. Place in the refrigerator to chill. Work on second tenderloin package.
6. Once both steaks are firming up in the refrigerator, place another large piece of plastic wrap on a cutting board.
7. Roll out defrosted puff pastry sheet, dust with flour if necessary. Cut pastry in half.
8. Remove steaks from the refrigerator and place them in the centre of each puff pastry sheet. Carry the long end of the pastry over to cover the steak. Wrap both ends underneath the steak and press to seal. Use a small amount of water to seal the edges if needed.
9. Use a piece of plastic wrap to firmly seal the pastry wrapped steak and firm up for about 5 minutes in the refrigerator.

Egg Wash

1. In a small bowl whisk an egg with milk.

Oven

1. Preheat oven to 400F.
2. Line a baking sheet with parchment paper, lay beef wellington steaks seam side down and brush tops and sides with egg wash.
3. Use a knife to score the tops of the pastry to allow steam to escape while cooking in the oven.
4. Sprinkle with salt on top and bake in the oven for 20 minutes.
5. The internal temperature of the steak will be ready to remove from the oven at 140F, where it will climb to 145F, a perfect medium rare, during the cooling process.
6. Allow to rest 10 minutes before slicing.