Peel the potatoes, celery and carrots. Wash everything and cut into cubes. Trim and wash the leek and remove the dark green. Cut the rest of the stick into pieces as thick as your thumb. Dice the ham.
Heat the butter in a large saucepan and fry the ham in it. Add the potatoes and vegetables and fry lightly. Now pour in 1 liter of meat stock, add the peppercorns and bay leaf and cook everything very soft for about 30 - 40 minutes. Cooking time depends on how firm the potatoes and vegetables are.
Then remove the bay leaf. Puree the soup in a blender or with the brisk Lotte and put back in the pot. Add so much of the other meat broth until the desired thickness of the soup is reached. Season the soup with freshly ground pepper, nutmeg and salt.
Warm the sausages in hot water, cut them into pieces and place them on preheated plates. Pour the soup over the sausages and put 1 tablespoon of sour cream on each plate.