Clean the cauliflower, wash it and cut it into small florets. Peel, wash and cut the kohlrabi into strips. Clean and wash mangetouts and spring onions. Cut mangetouts lengthwise into 2-3 strips, spring onions into rings.
Cook the mangetouts in boiling salted water for 3-4 minutes, drain. Bring 3/4 litres of water to the boil. Add 50 g cream. Season with salt and nutmeg. Cook the cauliflower florets for about 7 minutes, the kohlrabi for 5 minutes.
Drain and collect the stock. Melt the fat. Sauté spring onions in it. Add flour and sweat. Deglaze with vegetable stock and 100 g cream. Bring to the boil while stirring constantly. Cut Kabanossi into fine slices.
Add the pre-cooked vegetables and kabanossi to the soup and simmer for another 2-3 minutes. Season to taste with salt and pepper. Sprinkle with chervil.