Step 1

Heat the butter and oil together in a large skillet over med/high heat until hot but not smoking.

Step 2

Season the beef tenderloin with kosher salt and pepper. Add the tenderloin to the pan and brown on all sides, about 4-6 mins total. Remove to a plate to cool. Cut the ties and remove them.

Step 3

If there are blackened bits in your pan, use a paper towel to remove them and add a little more butter/oil. Otherwise add the shallots, garlic, and mushrooms directly to the pan and season with salt and pepper. (I use my food processor to mince the shallot, garlic, and mushrooms.)

Step 4

Add the parsley and thyme and cook over medium heat until the mushroom mixture begins to brown and all moisture has evaporated, about 8-10 mins.

Step 5

Lay out a long piece of plastic wrap and lay half of the prosciutto slices in a long layer (a little longer than the length of the tenderloin). Smear half of the mushroom mixture over the prosciutto and lay the tenderloin on top.

Step 6

Cover the top of the tenderloin with the remaining mushroom mixture and lay the remaining prosciutto over the top. The prosciutto should hang over the sides to cover.

Step 7

Use the plastic wrap to help you encase the tenderloin fully with the mushrooms and the prosciutto as the final layer.

Step 8

Wrap the tenderloin up tightly and chill in the refrigerator for about an hour.

Step 9

Preheat the oven to 450 degrees.

Step 10

Thaw the sheet of puff pastry until pliable and then roll it out on a lightly floured surface. Roll the puff pastry out using the tenderloin as your guide for size. The pastry should be large enough to wrap fully around the tenderloin and seal.

Step 11

Once the pastry is rolled (use two puff pastry sheets if you have a bigger tenderloin), remove the tenderloin from the plastic wrap and lay in the center of the puff pastry.

Step 12

Beat the egg with a little water and moisten the edges of the pastry. Fold the pastry tightly around the tenderloin and seal. Brush the seamed side with the egg wash and place on a parchment lined sheet tray, seam side down.

Step 13

Brush the rest of the pastry with the egg wash and cut a few slits on the top to vent.

Step 14

Roast the beef wellington for 15 mins, then reduce the heat to 400 degrees and roast for 25 - 30 mins more for medium rare. The beef should have an internal temp of 125 - 130 degrees when a thermometer is inserted into the center.

Step 15

Cover and allow the beef to rest at least 15 mins before slicing and serving.

Step 16

Heat the oil in a medium saute pan and add the shallot. Cook for about 5 mins over medium heat until soft and golden. Add the red wine, increase the heat to med/high and cook until the wine is reduced by about 2/Add the stock and continue to cook for another five minutes.

Step 17

Strain the sauce using a fine mesh strainer and discard the solids. Return the sauce to the pan over medium heat.

Step 18

Swirl in the butter one pat at a time until each piece is fully dissolved. Season with salt and pepper. Sauce should be slightly thickened and glossy.

Step 19

Slice the Wellington into thick pieces and serve with the red wine sauce.