Peel and chop the onion. Clean, wash and cut the leek into rings. Heat the oil in a large pot. Fry onion and leek for about 5 minutes.
Lightly pluck the sauerkraut, add and braise vigorously for about 5 minutes, turning. Stir in tomato paste and sweat it. Add bay leaf and juniper berries
Deglaze with 1 1/2 l water, bring to the boil and stir in the stock. Let everything simmer for about 10 minutes. Sprinkle in mashed potato powder and bring to the boil again
Cut the sausages into slices and heat them in the soup. Season with salt, pepper, paprika and sugar. Arrange on plates with 1 blob of crème fraîche