Trim fat from brisket of beef. Season both sides of meat with garlic salt, onion salt, celery salt and liquid smoke. Seal in container and marinate overnight in refrigerator. Wrap meat in foil and bake at 250 degrees for 4-5 hours.

SAUCE:

2 c. ketchup
1/2 c. cider vinegar
1/2 c. sugar
4 tbsp. liquid smoke
1/2 c. Worcestershire sauce

Combine above ingredients in medium saucepan. Bring to a boil then reduce heat and simmer for 20 minutes. Serve over cooked beef brisket.