Filet de Boeuf Wellington à la Périgourdine: Cœur de Filet de Bœuf en Croûte Dorée, Sauce Périgord aux Truffes Noires et Foie Gras

Season the Beef Tenderloin: Pat the beef tenderloin dry with paper towels. Season generously all over with sea salt and freshly ground black pepper.

Sear the Beef: Heat 2 tablespoons of olive oil in a heavy-bottomed skillet over high heat until shimmering. Sear the beef tenderloin on all sides until deeply browned, about 2-3 minutes per side. Remove from heat and immediately brush all over with Dijon mustard. Let cool completely on a wire rack.

Prepare the Duxelles: In the same skillet, melt 2 tablespoons of unsalted butter over medium heat. Add the finely chopped cremini mushrooms, minced shallots, and minced garlic. Cook, stirring frequently, until all moisture has evaporated and the mixture is deeply golden and fragrant, about 15-20 minutes. Stir in the fresh thyme leaves. Season with salt and pepper. Spread the duxelles on a plate to cool completely.

Assemble the Wellington: Lay a large piece of plastic wrap on a clean work surface. Arrange the prosciutto slices in an overlapping rectangle, large enough to envelop the beef. Spread the cooled duxelles evenly over the prosciutto. Carefully spread the foie gras pâté over the duxelles layer. Place the cooled, mustard-coated beef tenderloin at one end of the prosciutto-duxelles-foie gras layer. Using the plastic wrap, carefully roll the prosciutto, duxelles, and foie gras around the beef, ensuring it's tightly wrapped. Twist the ends of the plastic wrap to create a firm cylinder and refrigerate for at least 30 minutes to firm up.

Wrap in Pastry: Lightly flour your work surface. Roll out the chilled puff pastry into a rectangle large enough to completely encase the beef parcel. Remove the beef from the plastic wrap and place it on the pastry. Carefully bring the pastry up and over the beef, trimming any excess and sealing the edges firmly. Ensure there are no gaps. Place the seam-side down on a parchment-lined baking sheet. Optionally, decorate the top with pastry trimmings. Brush the entire surface with the beaten egg yolk.

Bake the Wellington: Preheat your oven to 200°C (400°F). Bake the Wellington for 30-35 minutes for medium-rare (internal temperature of 52-54°C / 125-130°F), or longer for desired doneness. The pastry should be golden brown and puffed. Let the Wellington rest for at least 10-15 minutes before slicing to allow the juices to redistribute.

Prepare the Périgord Sauce: While the Wellington bakes and rests, melt 1 tablespoon of unsalted butter in a small saucepan over medium heat. Sauté the finely minced shallot until softened, about 2 minutes. Pour in the Madeira wine and reduce by half. Add the beef stock and simmer gently until the sauce has reduced by about one-third and slightly thickened, about 10-15 minutes. Stir in the finely diced fresh black truffle (or truffle paste). Season with sea salt and freshly ground black pepper to taste. Keep warm.

Serve: Slice the Filet de Boeuf Wellington into thick portions using a sharp, serrated knife. Serve immediately with a generous spoon of the exquisite Périgord sauce.