Cut the sprouts in half long ways. Boil water and cook the sprouts until they turn a brighter green about 10 minutes. While this is happening get a pan hot and start to cook the bacon and the onions. When the onions start to form water drops on the outside add the sprouts. Cook until brown starts to form on the sprouts, and the onions are soft. Add the butter, garlic, sugar, salt, pepper, and then the vinegar. Once a sauce forms it is ready to serve.