Cut or slice the onion into thin rings. Heat the oil in a pot. Fry the onion rings in it while turning them golden brown and take them out
Wash the potatoes and carrots and cut into small cubes. Briefly sauté the potatoes and carrots in hot frying fat. Deglaze with about 300 ml water. Bring to the boil and stir in the stock. Add deep-frozen soup vegetables and possibly marjoram and cook covered for about 15 minutes.
Wash parsley, shake well dry and chop finely. Cut the sausages into thin slices. Add sausage slices to the soup and heat up
Season potato soup with salt, pepper and possibly marjoram. Sprinkle with onion rings and parsley before eating