For the sauerkraut soup, rinse the sauerkraut, squeeze, finely chop. Peel the raw potato, cut into small cubes. Cook the sauerkraut and potato together, covered with plenty of water, in the soup pot for 30 minutes.
Cut ham or bacon and onions into small cubes, fry in a pan with a little lard until golden brown and add to the soup together with the frying fat. Stir, bring the sauerkraut soup to the boil again, serve very hot.