Put the beans in a colander and drain. Peel the onion and cut into fine cubes, also dice the bacon or buy it already diced. Wash the parsley and cut into small pieces or chop.
Heat the oil in the pan and sweat the bacon and onions in it. Deglaze with the white wine vinegar and the stock. Then let it cool down a bit.
In the meantime, put the beans in a salad bowl. Add salt, pepper and sugar and stir. Then add the ingredients from the pan. Mix and let steep for half an hour.
Fresh white bread tastes particularly good when lightly toasted in the oven.