Clean the pointed cabbage, cut out the stalk in a wedge shape. Wash the pointed cabbage, drain and cut into 2-3 cm long strips. Peel onions and cut into thin rings. Peel and wash potatoes and cut them into pieces.
Quarter the apple, remove the core, cut the quarters into slices. Peel thin skin from the blood sausage. Halve sausage lengthwise and cut into approx. 0.5 cm thick slices.
Heat the oil in a large frying pan. Fry the potatoes for about 10 minutes while turning. Add pointed cabbage and fry for about 2 minutes. Add onion rings, black pudding and apple slices and fry for another 3-4 minutes.
Wash the marjoram, shake dry, remove the leaves. At the end of the frying time, add 1 tsp. mustard and marjoram to the pan. Season to taste with salt and pepper. Stir the rest of the mustard with sour cream until smooth and add to the pan.