In a hot frying pan lightly sear the seasoned beef filet on all sides. Chill in freezer for 5 minutes.
Roll out 2ft of plastic wrap on a countertop. Lay down the prosciutto uniformly over the plastic and evenly spread a layer of the truffle puree on top.
Remove the filet from the freezer and liberally brush all over with the mustard.
Roll the filet in the prosciutto and continue to wrap the plastic around to make a cylindrical shape, put in the refrigerator for 10 minutes.
Whisk the eggs in a small bowl and set aside.
Unwrap the filet from the plastic. Lay out the sheet of pastry and brush the sides with the egg wash. Lay the filet down in the middle of the pastry.
With the edge closest to you, wrap the pastry around and trim and crimp the edges, brush liberally and with the egg wash.
Place in the oven and bake for 26 minutes. Remove and allow to rest for 5 minutes.
