Spread center of R.W.(foil) with butter or margarine. Cut steak into serving portions. Arrange on foil, slightly overlapping each portion. Sprinkle with onion soup mix, mushrooms, gr. pepper, tomatoes, seasonings. Mix juice, A-1 sauce and cornstarch. Pour over meat and vegetables. Bring foil up over and double-fold edges to seal tightly. Bake 2 hours in 365° oven. Roll back foil and sprinkle with parsley. Makes 4 generous servings.