Blend mustard with tomato sauce, corn syrup, vinegar, onion, Worcestershire, celery seed and hot sauce. Cook over med heat, stir frequently, till mixture comes to boil; reduce heat and let simmer gently for 30 mins.
Mix beef, crackers, egg, garlic powder, chopped onion, and ketchup together. Make into hamburger patties, and cook on grill.
Let cooked hamburgers marinate in sauce mixture over night,
Preheat oven to 350 degrees F (175 degrees C)
Reheat burgers, in sauce, 30 minutes or until heated through, in oven and enjoy!