Preheat oven to hot (400°F.).

Lightly grease the center of four pieces of heavy-duty aluminum foil with one tablespoon of the butter. Place a steak on each piece of foil. Season with salt and pepper.

Sauté the shallots in the remaining butter until translucent. Add the mushrooms. Cook for five minutes.

Add the wine, lemon juice and parsley and continue to cook until most of the liquid has evaporated. Spoon the mixture over the fish. Season with salt and pepper to taste.

Draw the edges of the foil together and seal the packages. Bake for twenty minutes, or until fish flakes easily when tested with a fork. Serve in the foil.