Peel, wash and roughly dice the potatoes. Clean, wash and cut leek into rings. Boil 1.5 l water with broth. Add potatoes and leek, bring to the boil and simmer covered for about 15 minutes.
Wash the chives, shake dry and cut into small rolls. Coarsely chop the stremel salmon. Coarsely puree the vegetables in the stock.
Stir half of the cheese into the soup, season with salt and pepper. Serve the soup with salmon, remaining cheese and chives.