Beef Wellington

Directions

1. 1
   Heat the oven to 425°F. Place the beef into a lightly greased roasting pan. Season with the black pepper, if desired. Roast for 30 minutes or until an instant-read thermometer inserted into the beef reads 130°F. Cover the pan and refrigerate for 1 hour.
2. 2
   Reheat the oven to 425°F. Beat the egg and water in a small bowl with a fork.
3. 3
   Heat the butter in a 10-inch skillet over medium-high heat. Add the mushrooms and onion and cook until the mushrooms are tender and all the liquid is evaporated, stirring often.
4. 4
   Sprinkle the work surface with the flour. Unfold the pastry sheet on the work surface. Roll the pastry sheet into a rectangle 4 inches longer and 6 inches wider than the beef. Brush the pastry sheet with the egg mixture. Spoon the mushroom mixture onto the pastry sheet to within 1-inch of the edge. Place the beef in the center of the mushroom mixture. Fold the pastry over the beef and press to seal. Place seam-side down onto a baking sheet. Tuck the ends under to seal. Brush the pastry with the egg mixture.
5. 5
   Bake for 25 minutes or until the pastry is golden brown and an instant-read thermometer inserted into the beef reads 140°F.