Prepare barbecue sauce. To butterfly loin, split meat lengthwise almost all the way to opposite side, then spread open flat. Pound out to a 15x10 inch rectangle, about 3/4 inch thick. Brush top with 1/4 cup of the barbecue sauce.

Combine ground beef, onion, garlic, salt, pepper and an additional 1/4 cup of the barbecue sauce. Spread evenly over roast. Press mushrooms into ground beef. Sprinkle bread crumbs and parmesan cheese over meat. Starting from 1-inch side, roll up and tie. Place on rack in shallow roasting pan. Roast, uncovered, in 325 degrees oven for about 2 1/2 hours. Baste with additional barbecue sauce during last 15 to 20 minutes of roasting.

Pass remaining barbecue sauce. Garnish with celery leaves, if desired.

Makes 6 to 8 servings.

Barbecue Sauce: In medium saucepan combine ketchup, chili sauce, wine vinegar, packed brown sugar, lemon juice, worcestershire sauce, steak sauce, mustard, salt, pepper and garlic. Simmer 30 minutes. Remove from heat.

Makes 2 2/3 cups sauce.