I searched around for a good base recipe for this, and as usual ended up pulling tips from various ones until I felt like I had a fairly simple plan. It turned out great!

Ingredients

3-4 tablespoons oil

Beef tenderloin (1 piece for each person - the other ingredients listed assume you have about 4 normal portions)

2 tablespoons butter, softened
2 tablespoons butter
1 onion, chopped
1/2 cup sliced fresh mushrooms
2 ounces liver pate
2 tablespoons butter, softened
salt and pepper to taste
1 (17.5 ounce) package frozen puff pastry, thawed
1 egg yolk, beaten
1 (10.5 ounce) can beef broth
2 tablespoons red wine

Directions

Preheat oven to 450 degrees F.

Remove frozen puff pastry from the freezer and let thaw at room temperature approximately 40 minutes. This works out pretty close to the time you will work on other steps until you need the pastry.

Put oil in a stock pot and heat on high. Add beef 1 at a time and sear briefly on all sides until brown. Place seared beef pieces in a baking dish.

Spread with 2 tablespoons butter on beef pieces and bake for 10 to 15 minutes. The internal temperature should not be greater than 110 F or so.

Put in refrigerator to cool.

Melt 2 tablespoons butter in a skillet over medium heat. Saute onion and mushrooms in butter for 5 minutes. Remove from heat, and let cool.

Mix together pate and 2 tablespoons softened butter, and season with salt and pepper.

Some recipes said to "roll out" the puff pastry dough. I didn't know how much to roll, how thin to get it, or anything else so I ignored this step completely. I simply unfolded the pastry dough and used it. There are 2 pieces of dough per package. I had pretty decent sized steaks so I just used 1 whole piece for each steak (I cut some off after folding though).

Lay a piece of pastry on wax paper, and spread a tablespoon or so of the pate mixture into the center. Spread it around an area about as big as your steak.

Put a tablespoon or two of the mushroom/onion mixture on top of the pate you just spread.

Set one of the steaks on top of the little pate/mushroom bed you just made.

Spread some more of the pate over the beef, making sure to get some on hte sides. Top with more of the onion and mushroom mixture.

Fold up (starting with the long edges) and seal all the edges, making sure the seams are not too thick. Cut off excess that gets in the way.

Place beef in a lightly greased baking dish big enough to hold all the pieces without touching. If necessary, use 2 dishes.

Important! Cut a few slits in the top of the dough, and brush with beaten egg yolk.

Bake at 450 degrees F for 10 minutes, then reduce heat to 425 degrees F for 10 to 15 more minutes, or until pastry is a rich, golden brown and meat is around 130 degrees at its thickest point.

Set aside, and keep warm.

Place all reserved juices in a small saucepan over high heat. Stir in beef stock and red wine; boil for 10 to 15 minutes, or until slightly reduced. Strain, and serve with beef.