In a pan, fry the bacon pieces and onion on the stove over medium heat, stirring frequently, for 6 to 8 minutes, the bacon and onion should be golden brown. Remove the bacon / onion mixture from the pan, drain on a paper towel, leave any excess fat in the pan.
Put the green beans in the pan and fry them in the bacon fat over medium heat for 8 to 10 minutes, they should be soft but still have a bite. Add vinegar, sugar and bacon mixture, mix everything well, simmer again for 3 minutes, stirring frequently. Season with salt and pepper, arrange on a plate and serve.
All types of meat, poultry and potatoes go well with it.