Peel and wash the carrots and celery. Cut 1 carrot and celery into pieces. Clean and wash the leek and cut it into rings. Peel and roughly chop the onion. Wash and clean the tomatoes and cut them into pieces.
Heat the oil in a pot. Fry celery, carrot pieces, leek, tomatoes and onion for about 5 minutes. Deglaze with 1 1/4 litre of water, add 1 teaspoon of salt, bring to the boil and simmer at low heat for about 45 minutes.
Prepare rice in boiling salted water according to package instructions. Wash the mangetouts. Cut 2 carrots and sugar snap peas into fine strips. Drain rice. Wash the chervil, dab dry, pluck the leaves from the stalks and chop them finely.
Pour vegetable stock through a sieve into a pot. Season to taste with salt, pepper and some sugar, bring to the boil. Press the sausage meat as small dumplings from the skin into the broth. Add vegetable strips and rice, let everything simmer for 3-5 minutes.
Arrange soup in plates, sprinkle with chervil.