Hamburg and Beans Casserole

1 lb cooled hamburg

1/2 cup chopped onions

1 (1 lb, 12 oz) can baked beans of your choice

1 (1 lb) can red kidney beans, drained

1 (1 lb) can white kidney beans, drained

1/2 cup sugar

3/4 cup brown sugar

1/2 cup ketchup

1 tsp dry mustard

2 tsp vinegar

Mix all ingredients and bake 40 minutes at 350 degrees.