Beef Wellington

Mushroom Duxelles

1. In a large sauté pan over medium heat, add 2 tablespoons olive oil and the mushrooms. Cook until the mushrooms are tender and liquid starts to evaporate. Deglaze with a bit of red wine.
2. Add the red wine and cook until the alcohol evaporates. (If you smell the mixture, the alcohol should not burn in your nose.)
3. Add butter and garlic; sauté until the garlic is tender. Season with thyme, black pepper, and sea salt.
4. Place mushrooms in a food processor and pulse until the mixture is a fine paste. Remove from the food processor and season with chopped thyme. Adjust seasoning, if needed, with various herbs, truffles, and cooked foie gras. 

Searing Meat

1. Place a large skillet on a burner over high heat. Once the pan is hot, add 1 tablespoon neutral oil or clarified butter or ghee.
2. Meanwhile, season the trimmed tenderloin with kosher salt on all sides.
3. Slowly place the tenderloin into the pan. Allow to sear over high or medium-high heat until golden brown. Rotate the sides so that it has even golden-brown searing all around. Safety Tip: Place the tenderloin in the pan closest to you first and then gently lay the remainder down away from you. If there is any spatter, it will go away from you instead of toward you.
4. Once seared, remove from heat and season with black pepper. Let the tenderloin rest about 5 to 10 minutes, then put it in a cool place, such as the refrigerator, to stop cooking and cool completely.  If doing the day before, cover the tenderloin with plastic once cooled.

Sauce

1. Use the same pan you seared the meat in and turn the heat off or to low. Add the garlic and shallot to any residual fat in the pan and gently sauté until tender. (If there is not any fat, add 1 teaspoon of butter.) Once the shallot is tender, add the wine and thyme; cook until the alcohol is burned off. 
2. Add the demi-glace. Simmer together on low heat until the sauce is flavorful, approximately 20 minutes. 
3. Meanwhile, add the cornstarch and water together in a bowl and whisk together to make a slurry. Bring the sauce to a boil, slowly whisk in the slurry, and continue to cook until the sauce thickens. 
4. Strain the sauce through a fine mesh sieve or strainer. Season with salt and freshly cracked pepper. Cool the sauce until ready to use. 

Pre-Assembly of Wellington

For first phase of assembly, you will need: Seared and cooled tenderloin of beef, mushroom duxelles, sliced prosciutto, and plastic wrap

1. Give yourself a lot of space. Unravel approximately 2' of plastic wrap starting from the counter’s edge and moving away from you.
2. Line the prosciutto about 4" away from start of plastic wrap (i.e., 4" away from counter’s edge) on the left. Start the second layer approximately 1" from the left and shingle with the remaining prosciutto so that it overlaps. The line of prosciutto should be approximately ½" longer than the tenderloin on either end.
3. Cover the prosciutto with the mushroom duxelles, leaving about a ½" border on all edges of uncovered prosciutto. Flatten the mushroom duxelles so that it is evenly spread.
4. Smear Dijon mustard evenly over tenderloin. Place the tenderloin on the edge of the prosciutto closest to you. Lift the plastic up and over the tenderloin and keep it tight. Roll it over halfway, tightening if needed so that the prosciutto and duxelles is very tight against the meat. Gently pull back any plastic that is going past the prosciutto and onto the tenderloin; as you continue rolling, the prosciutto from the beginning should overlap the other prosciutto/duxelles. Continue peeling the plastic away from the meat/mix; you are using the plastic as a guide to tightly wrap the prosciutto/duxelles mix around the meat. Once the edges of the prosciutto have met and are tight, continue to roll allowing the plastic to roll over itself. Twist the right and left ends of the plastic to help tighten the roll. Chill in refrigerator for at least 30 minutes, up to one day. 

Wellington Assembly

For this step you will need the following: Puff pastry (defrosted, but cold), flour, egg yolk (mixed in a bowl), pastry brush, rolling pin, paring knife, and prosciutto/duxelles-wrapped tenderloin

1. Unfold puff pastry, place on a lightly floured flat surface, and gently roll out to about ¼" thickness. If one sheet is not enough, adjoin a second sheet to make a larger rectangle so that the puff pastry is large enough to roll around the tenderloin.
2. Brush the edges of the puff pastry with egg yolk. Unwrap the tenderloin from the plastic, being careful that all plastic is removed. Place the tenderloin on puff pastry, about 1" from the edge closest to you. Roll the puff pastry around the tenderloin. Be sure that the puff pastry overlaps by approximately ½" to 1", and this area has been egg washed to glue the pastry together. Trim any excess. 
3. Egg wash the right and left edges of the puff pastry and fold under the Wellington. Be careful to limit the pastry that overlaps, as it will take longer to cook. Place the Wellington on a wire resting rack, that sits on a cooking sheet or dish.
4. Brush egg yolk evenly over the entire Wellington. Sprinkle with sea salt. Optional: Use extra puff pastry to cut out and make any designs or patterns. Glue on with egg wash. 
5. Chill in refrigerator for at least 1 hour and up to one day.

Baking of Wellington

1. Preheat oven to 400°F.
2. Remove the Wellington from the refrigerator. Brush again with egg wash and sprinkle with sea salt. Score the Wellington with a small knife, being careful not to cut all the way through the pastry. You can cut designs into the pastry as well.
3. Cook in the preheated oven for 20 minutes, at which point, the crust should be evenly golden. Check the internal temperature of the meat. Remove from the oven if it has reached 120°F. Otherwise, reduce the oven temperature to 375°F and continue to cook until the meat reaches an internal temperature of 120°F for medium rare. Remove the Wellington from the oven and allow to rest for approximately 15 minutes, as it will continue to cook thus reaching 125°F for medium rare. While the meat rests, warm the sauce.
4. Slice meat into 1" slices, season again with fleur de sel, and serve with sauce.