Remove the peel from the potatoes and cut into small cubes. Remove the peel from the onions and chop finely. In a soup pot, leave the butter out and lightly brown the potatoes and onions in it. It should not turn brown.
1 Pour 500 ml of tap water, add the stock cubes and cook on the stove for 25 minutes with the lid closed. Strain through a sieve or alternatively work through with an electric mixer to a uniformly creamy liquid. Add the sour cream and grated cheese, heat while stirring throughout until the cheese is dissolved around it. Season with salt, marjoram and pepper.
Serve with: toasted slices of white bread with a touch of garlic.