Instructions:
1. Put the sauerkraut together with the pickling liquid in a casserole, pour in stock (or water), add caraway seeds, bay leaf, allspice and cook for approx. 20 minutes until soft.
2. In the meantime, prepare a light roux. Melt butter with oil in a heated pan, add finely chopped onions, fry briefly until soft but not coloured, sprinkle with flour, fry intensely and remove from heat.
3. Cook peeled potatoes diced into small pieces in a saucepan.
4. Add the boiled potatoes together with water to the sauerkraut which is now soft, thicken with the prepared roux, add previously soaked mushrooms, add some milk and cook again for several minutes.
5. Fry the ham slices on a frying pan until crisp and use a mixer to mix the fried slices in a little warm milk to make foam.
6. Before serving, garnish the soup with sautéed mushrooms, pour milk foam on top and sprinkle with chopped parsley leaves.