Season the beef generously with salt and pepper. Sear in a hot skillet with olive oil until browned on all sides. Remove and let rest; this seals in flavor and keeps the center juicy.

Make the mushroom duxelles. In the same pan, sauté mushrooms with butter, garlic, and thyme until most of the moisture evaporates. Hit it with a pinch more salt, then cool.

If you’re going all-out, lay prosciutto on a sheet of plastic wrap, spread the mushroom mix over it, and roll into a log. Chill for 15 minutes to set the shape (optional but delightful).

Brush the cooled beef with Dijon mustard. Ready your puff pastry on a lightly floured surface. If you went with the prosciutto log, unwrap and place it in the center of the pastry.

Wrap the beef with the pastry, trimming edges as needed. Seal all seams with the beaten egg wash. Chill again for 10–15 minutes to help it hold its shape.

Preheat the oven to 400°F (200°C). Brush the pastry with more egg wash for a glossy finish. Bake about 20–25 minutes, or until the pastry is golden and the internal temp hits your preferred doneness (125°F for medium-rare).

Let rest for 10 minutes before slicing. The waiting payoff is real—juicy beef wrapped in crisp pastry, no knife-wrestling required.