Clean, wash and drain the kohlrabi, mangetouts and pointed cabbage. Cut kohlrabi into thin slices, pointed cabbage into strips. If necessary, halve sugar snap peas. Peel and wash the potatoes and cut them into small cubes.
Peel and finely dice the shallot.
Heat the oil in a large pot and sauté the shallots in it. Add kohlrabi and potatoes, fry briefly and season with salt and pepper. Add 1 1/2 litre of hot water, bring to the boil, cover and simmer for about 5 minutes.
Add the pointed cabbage, mangetout and peas to the soup, bring to the boil again and simmer covered for 6-8 minutes. Wash the chervil, shake dry and pluck off the leaves.
Stir the cream and about 3/4 of the chervil leaves into the soup, season with salt, pepper and lemon juice. Serve the soup, sprinkle with the remaining chervil leaves.