3/4 c. white wine
1/4 c. chopped onion
4 tbsp. butter
2 tbsp. soy sauce
1 tsp. dry mustard
Pepper to taste
2 1/2 - 3 lbs. beef tenderloin

Place beef tenderloin in a shallow baking dish and dot with 2 tablespoons butter. Place onions and remaining butter in a small frying pan and saute until transparent. Add the remaining ingredients and bring to a boil; pour over the meat. Let marinate at least 1 hour. Transfer meat to a baking rack and place in a 425 degree oven for approximately 25 minutes, for medium rare.