3 to 4 lb. pot roast (about 2 or 2 1/2 inches thick)
1/2 c. chopped onions
1/2 c. vinegar
1/4 c. salad oil
1/2 tsp. celery salt
1 tsp. salt
1/2 tsp. pepper
1/2 tsp. oregano
1/2 tsp. thyme
1/2 tsp. rosemary
garlic salt

Place meat in glass or clay container, NOT metal. Sprinkle garlic salt on both sides of meat. Mix remaining ingredients and pour over meat to marinate. If meat is frozen, start the night before and let set at room temperature. If it is thawed, start night before and let set in refrigerator that night and put out at room temperature the next day.

Place beef on grill; baste with marinade sauce several times during cooking. Check carefully for desired doneness.