Heat oven to 325°F. In ungreased 13x9-inch (3-quart) glass baking dish, combine tomatoes, gravy and barbecue sauce; blend well. Add corn and onion; mix well. Place beef pieces in mixture; spoon mixture over beef. Cover with foil.
Bake covered at 325°F. for 1 hour 30 minutes or until beef is fork-tender. Sprinkle with parsley. To serve, spoon mashed potatoes into individual shallow bowls. Top each with beef and vegetable mixture.