Wash the potatoes thoroughly. Heat the fat in a frying pan and fry the potatoes for 2 minutes while turning. Deglaze with 1/4 litre water, add stock and cook covered for about 20 minutes.
Wash, clean and chop the spring onions and tomatoes. Remove the skin from the sausage, quarter it lengthwise and cut into slices. Wash marjoram and pluck off leaves. After about 10 minutes add vegetables and sausage to the potatoes.
Season with salt and pepper. Serve sprinkled with marjoram.