Ingredients:
For the Filling:
- 1 pound (450g) beef tenderloin, trimmed
- Salt and pepper, to taste
- 2 tablespoons olive oil
- 1 tablespoon Dijon mustard
- 8 slices prosciutto
- 1 cup mushroom duxelles (finely chopped mushrooms cooked with garlic and herbs)
- Puff pastry sheets (store-bought or homemade)
For the Egg Wash:
- 1 egg
- 1 tablespoon water