Peel and finely chop the onion. Heat the oil in a pot and fry the onion until transparent. Add the sauerkraut and sauté briefly. Deglaze with white wine and 1 litre water. Add stock cubes, bay leaf, allspice and clove.
Bring to the boil. Peel the potatoes and grate them into the soup. Wash and clean the peppers, cut them into strips, add them to the soup and cook them for another 5 minutes. Flavour with salt, pepper and sugar.
Cut the black pudding into slices and heat in the soup just before serving. Fill the soup into plates and add 1 teaspoon of crème fraîche to each plate. Sprinkle with paprika.