Preheat oven 325 degrees Fahrenheit.
In a large mixing bowl, combine ground beef, cracker crumbs, salt, pepper, egg, onion and tomato sauce.
Mix lightly.
Shape into a loaf and place in a baking dish.
In a small mixing bowl, combine the ketchup, brown sugar, water, mustard and vinegar.
Brush the loaf with this mixture.
Place meat loaf in oven and bake 1 hour and 15 minutes, basting occasionally with sauce.