Clean and wash the leek and cut into thin rings. Melt a tablespoon of fat in a pan. Add the sauerkraut, leek and bay leaf and stir-fry for about 5 minutes. Pour in the stock and braise for 20-30 minutes. Season to taste with pepper.
Fry the sausages in the remaining fat until golden brown. Bring 120 ml water and salt to the boil. Remove from the heat and add milk, stir in the puree flakes. Arrange sauerkraut with sausages, puree and tomato quarters on a plate. Sprinkle with chopped parsley