Mix liquid smoke, garlic salt, onion salt, celery salt and Worcestershire
sauce. Sprinkle brisket with pepper. Cover both sides of meat with sauce in
a baking dish. Cover tightly with foil and place in refrigerator overnight.
The next day, bake (covered) at 300 degrees F for 5 hours.
Add barbecue sauce after 4 hours and leave uncovered from then on.