In a large bowl or shallow dish, combine the Worcestershire sauce, chili powder, bay leaves, garlic, celery salt, pepper and, if desired, liquid smoke. Cut brisket in half; add to bowl and turn to coat. Cover and refrigerate overnight., Transfer beef to a 5- or 6-qt. slow cooker; add broth and bay leaves. Cover and cook on low for 6-8 hours or until tender., For sauce, in a small saucepan, saute onion in oil until tender. Add garlic; cook 1 minute longer. Stir in the remaining ingredients; heat through., Remove brisket from the slow cooker; discard bay leaves. Place 1 cup cooking juices in a measuring cup; skim fat. Add to the barbecue sauce. Discard remaining juices., Return brisket to the slow cooker; top with sauce mixture. Cover and cook on high for 30 minutes to allow flavors to blend. Thinly slice beef across the grain; serve with sauce. Freeze option: Place individual portions of sliced brisket in freezer containers; top with barbecue sauce. Cool and freeze. To use, partially thaw in refrigerator overnight. Heat through in a covered saucepan, gently stirring and adding a little water if necessary.