Cut the fennel, green onion, potato and garlic into small pieces. Fry in olive oil until everything takes on a little color. Then gradually add 1.5 liters of vegetable stock.
Cook until the vegetables are cooked through. Then add the sour cream with the spices, lemon juice and sugar and season to taste. Add 80 g of grated Parmesan and then whisk with the magic wand, season again to taste.