Drain beans and set aside. Fry onion with bacon strips, cut into small pieces. Mix in brown sugar, catsup, mustard (not dry mustard) and vinegar. Boil for a few minutes. Add beans and mix well. Place in 350 degree oven for one hour in covered dish. Stir after 1 hour, if still juicy leave off lid and place back into oven.
This can also be put into a crockpot and cooked on low for about 3 hours; remove lid and cook on high for one hour.