My mother used to make this from the garden fresh green beans. She never used a recipe; it was always based on how many green beans she got from the garden.

Slice green beans in 1/2-1" (approx.) pieces. Place them in water & cook til tender.

Put the cooked green beans in a bowl with a little bit of their cooking water.

Slice a small yellow onion in thin slices into the bowl with the beans.

Cook a couple slices of bacon. When done, crumble them. Add the bacon to the beans. Don't discard the bacon drippings.
In the same pan that you cooked the bacon, combine the drippings with one capful of vinegar and stir in 1 tsp of granulated sugar. You only have a small quantity of liquid here and need to quickly blend the mixture. Cook until the mixture thickens just a bit and pour over the beans and onions. Lightly toss. Serve warm.