Clean the red cabbage, quarter it and remove the stalk. Cut the cabbage into fine strips. Peel and quarter apples, cut out the core. Cut apple quarters into slices. Pour red cabbage and apples with red wine.
Crush the juniper and put it into a tea bag with cloves, cinnamon stick and peppercorns. Tie up with kitchen string. Add the spice bag to the red cabbage and leave to marinate for about 12 hours. Wash the duck, dab dry and place on the fat pan of the oven.
Season with salt and pepper and roast in the preheated oven (electric cooker: 200 °C/ gas: level 3) for about 1 1/2 hours. From time to time, pour the frying fat over it. In the meantime peel onions and cut them into fine strips.
Skim 3-4 tablespoons of cooking fat from the duck and heat in a saucepan. Sauté the onions in it. Add sugar, caramelise slightly and deglaze with vinegar. Add the red cabbage with liquid and simmer for about 45 minutes.
Season with salt and nutmeg. In the meantime stir dumpling powder into 3/4 litre cold water and let it swell for about 10 minutes. Cut toast into small cubes. Heat oil in a pan and fry the toast cubes in it until crispy.
Form approx. 12 small dumplings from the dumpling mixture and fill with toast cubes. Cook the dumplings in boiling salt water for about 20 minutes. Peel, wash and finely grate the potatoes and stir into the boiling red cabbage.
Add the cranberries and simmer for another 10 minutes. Keep duck warm in the oven. Loosen the roast with the chicken soup, pour through a sieve into a pot and bring to the boil. Stir starch with 1 tablespoon of water until smooth and bind the gravy.
Season to taste with salt and pepper. Warm quince jelly slightly and stir with balsamic vinegar until smooth. Spread the duck with it and glaze it in the oven for about 5 minutes. Carve the duck, arrange on plates with red cabbage and dumplings and garnish with marjoram.