At the beginning, the onion is sautéed with butter and oil in a soup pot. Then the potatoes are added and 2/3 of the cut leeks follow.
When the entire contents are nicely sweated, the pot is now filled with 0.6 l of water and the stock cube is now used. After simmering for 15 minutes, everything is mixed with the hand blender and the last remaining leek is added to the pot to cook and simmered for 5 minutes.
Finally, sour cream and cream substitute are added and heated a little (but no longer boiled!).