Sprinkle both sides of a 5-6 lb. brisket with celery, garlic, and onion salt. Pour over ½ bottle liquid smoke. Cover bowl tightly with foil. Let marinate overnight. Before cooking, sprinkle with salt and pepper and Worcestershire sauce.
Cover tightly and bake 5 hours at 275°. Cool and let fat congeal; scrape off and slice.
Bar-b-que: Cover with favorite sauce slices of brisket and bake 275° for 1 hour, basting occasionally.