To prepare, the zucchini are diced and the leek cut into small pieces.
Then an onion is chopped up and fried in a large saucepan with the olive oil. When the onion is lightly browned, add the zucchini and leek and cook for about 5 minutes with the lid closed. All of this is then extinguished with the vegetable stock and can simmer for another 10 minutes.
Finally add the milk and mustard and puree everything with the hand blender. Then just add salt and pepper to taste and serve with the sour cream and pine nuts.
Tip: I like it best with the medium-hot mustard from Bautz`ner.