2 lb. top sirloin, cut in long thin strips
1/4 lb. butter
2 lb. onions, thinly sliced
2 lb. mushrooms, sliced
2 tbsp. tomato paste
2 c. heavy cream or sour cream
1 1/2 tsp. salt
1/2 tsp. black pepper

Saute beef in half the butter until browned. Remove beef. Melt half of the remaining butter, saute onions 10 minutes. Remove. Melt remaining butter and saute mushrooms for 5 minutes. Return beef and onions to skillet, add tomato paste, then cream. Stir constantly. Cover and cook over low heat 30 minutes or until meat is tender. Season with salt and pepper. Serve over noodles or rice. Serves 6-8.