Clean and wash the soup greens. Cut half roughly. Peel and wash the potatoes and cut them into pieces. Heat the fat in a pot. Brown potatoes and roughly cut soup vegetables in it.
Season with salt, pepper and stock. Add 1 1/2 litres of water, bring to the boil and boil for about 15 minutes. In the meantime, finely dice the remaining soup vegetables or cut them into rings and cook them in a little salted water. Cut the sausages into slices.
Mash the potato soup. Add slices of sausage and soup greens with liquid and warm up. Arrange potato soup in plates and garnish with some crème fraîche.