All of these items are added in amounts to taste; if you like lots of bacon and onions, then cook a whole onion and 1/2 lb. of bacon. Do more or less according to your taste.
Fry diced bacon until crisp. Remove bacon from pan, then add chopped onions and fry in bacon grease until tender. Pour in vinegar (white or cider) to taste (again, a lot of vinegar if you like sour stuff, or very little for less flavor). Bring to a boil, and add bacon, stir mixture together. Then pour over cooked green beans, and stir again.
I hope you like it!