01 -
Preheat your oven to 400°F to prepare for baking the Wellington.
02 -
Generously season the beef tenderloin with salt and pepper.
03 -
Heat olive oil in a large pan over high heat and sear the beef on all sides until well browned, about 2 to 3 minutes per side.
04 -
Remove the beef from the heat and let it cool briefly. Once cool, brush all sides with mustard.
05 -
Chop the mushrooms finely, using a food processor if available.
06 -
In the same pan, sauté the mushrooms over medium-high heat until their moisture evaporates, approximately 10 to 15 minutes.
07 -
Lay out a large piece of plastic wrap. Arrange the ham slices on the wrap and spread the cooked mushrooms evenly over the ham.
08 -
Place the mustard-coated beef in the center and roll the mushroom and ham layer over the beef tightly, using the plastic wrap to help roll. Twist the ends of the plastic wrap to secure the shape. Refrigerate for 20 minutes.
09 -
Roll out the puff pastry on a lightly floured surface to a size sufficient to wrap the beef.
10 -
Unwrap the chilled beef and place it in the center of the pastry. Brush the edges of the pastry with beaten egg yolk. Fold the pastry over the beef, trimming excess to avoid excess layers, and seal tightly.
11 -
Place the pastry-wrapped beef seam-side down on a baking sheet. Brush with more egg yolk.
12 -
Use a sharp knife to lightly score the surface of the pastry, then sprinkle with flaky salt.
13 -
Bake in the preheated oven for 25 to 35 minutes until the pastry is golden brown and the internal temperature of the beef reaches 125°F to 130°F for medium rare.
14 -
Remove from the oven and let it rest for 10 minutes before slicing into 1-inch pieces.
15 -
Store leftovers in the refrigerator for up to 2 days. Reheat in a preheated oven at 350°F.