Peel and chop the onion. Wash and quarter the apple, remove the core. Cut apple into slices. Heat the fat in a pot and fry the onion with it until transparent. Add sauerkraut, apple, bay leaves, juniper berries, apple juice and stock.
Wash the marjoram, dab dry and chop half finely. Add to the sauerkraut, bring to the boil, cover and cook over medium heat for 20 minutes. Season sauerkraut with salt, pepper and sugar. Place the sausages in the sauerkraut and cook over a low to medium heat for 15 to 20 minutes (add some stock if necessary).
Then arrange the sausages on a preheated plate and garnish with the remaining marjoram. Serve with grated horseradish, mustard or gherkins and a hearty farmhouse bread.