Use a whole beef tenderloin to make about 10 servings. Remove any excess fat and cut into the tenderloin into one-to two-inch filets (figure B). Place one tablespoon of butter in a heavy skillet and heat the butter on high heat. Sear each filet on each side just until the outside is brown. Do not overcook--the filets should still be raw in the center.
After each filet is browned, place in the refrigerator while searing the rest of the filets.Lay out sheets of puff pastry dough, and trim along the fold lines to form a cross (figure C).
Spread about two tablespoons of the mushroom mixture in the center of the cross (figure D). Place a filet on top of the mushrooms and top with a very thin slice of pate (figure E) and another tablespoon of mushrooms (figure F) . Season with a little salt.
Fold the edges of the pastry dough together and pinch the edges to seal. Turn the mini-Wellington over so that it is seam-side down, then brush the top with a little beaten egg (figure G).
Continue until all the filets are wrapped. The individual portions can be refrigerated and cooked the next day, or frozen for later use.
To cook, preheat a baking sheet in a 375-degree oven. Cut small slits in the pastry dough to allow the steam to escape and gently place the Wellington seam-side down on the baking sheet. Bake until the pastry is golden brown--about 35 minutes to an hour, depending on how done you would like the filet.