Soak the sauerkraut briefly and then drain. Brown the sliced sausage in a pan, remove and set aside on a plate. Sauté the sauerkraut in the fat from the sausage, add 2 litres of water and cook for 40 minutes until tender. Thicken with the sour cream, and add a few drops of lemon juice and salt to taste. Brown the spare ribs in a little oil. Serve the soup with the sausage and spare ribs.