Cut the savoy cabbage into fine strips. Dice the onion and sauté in butter in a large saucepan. Add savoy cabbage and sauté briefly. Pour in the stock, season and cook for 30 minutes.
Take some savoy cabbage out of the pot and puree the rest.
Fold in the cream and curdled milk (or yogurt). Put the leftover strips of savoy cabbage back into the soup.
Squeeze out small balls from 2 fresh (coarse) sausages, fry them and add to the soup.
Variation: You can also add meatballs to the soup. To do this, fry walnut-sized balls made from 350 g of mixed minced meat, 1 egg, 1 roll, salt, pepper and paprika powder in hot fat.