01 -
Pat the beef tenderloin dry with paper towels and season generously with salt and pepper. Heat olive oil in a heavy pan over high heat. Sear the tenderloin on all sides until well-browned, about 2–3 minutes per side. Transfer to a plate and let cool for 10 minutes.
02 -
Brush all sides of the cooled beef tenderloin evenly with Dijon mustard. Set aside.
03 -
In a food processor, pulse mushrooms until finely chopped. Melt butter in a sauté pan over medium heat, add shallot and garlic, and cook until soft and fragrant. Add mushrooms and season lightly with salt and pepper. Cook, stirring frequently, until all moisture has evaporated and a thick paste forms, about 10–12 minutes. Set aside to cool.
04 -
Lay out overlapping prosciutto slices on a large piece of plastic wrap to form a rectangle. Evenly spread the cooled mushroom duxelles over the prosciutto. Place the beef on top and, using the plastic wrap, tightly roll into a log so beef is fully encased. Twist ends to secure and refrigerate for 15 minutes.
05 -
Preheat oven to 200°C. On a lightly floured surface, roll puff pastry into a rectangle large enough to encase the beef. Remove beef from wrapping and position in the center of the pastry. Fold pastry over beef, sealing seams and trimming any excess. Place seam-side down on a parchment-lined baking sheet.
06 -
Brush the surface of the pastry evenly with the beaten egg to ensure a golden finish. Chill for at least 10 minutes to allow pastry to firm.
07 -
Bake in the preheated oven for 25–30 minutes, or until the pastry is golden brown and an instant-read thermometer inserted into the beef reads 52°C for medium-rare. If necessary, tent loosely with foil to prevent overbrowning.
08 -
Remove from oven and let rest for 10 minutes. Transfer to a carving board, slice thickly, and serve immediately.