Trim off fat from brisket and sprinkle generously with onion, garlic and celery salt. Place inside large piece of foil, and set in oblong pan. Add about 3 ounces liquid smoke. Cover and refrigerate overnight. Pour off some of the marinade. Add a little pepper, and sprinkle with Worcestershire sauce. Wrap well in foil; place in pan and bake 5 hours at 300° F.
Remove from oven, and pour barbeque sauce over meat. Cover and bake one hour longer at 300° F.Servings: