Peel, wash and cut carrots and celery into pieces. Clean, wash and cut leek into rings. Peel and roughly chop the onions. Wash and clean the tomatoes and cut them into pieces.
Heat 2 tablespoons of oil in a saucepan. Sauté the vegetables for about 5 minutes. Deglaze with approx. 2 litres of water, add 1-2 teaspoons of salt, bring to the boil and simmer at low heat for approx. 45 minutes. Put flageolets in a sieve, rinse thoroughly and drain.
Cook the beans in boiling salted water for about 7 minutes. Wash parsley, dab dry, remove coarse stalks and chop leaves finely. Pour stock through a sieve into a pot, bring to the boil with the flageolets and simmer for about 2 minutes.
Season to taste with salt, pepper and a little sugar. Cut cabanossi into thin slices. Heat 1 tablespoon of oil in a coated pan. Fry the cabanossi in it in portions on each side for 1-2 minutes until crispy.
Drain the green beans and add to the soup. Arrange soup and fried cabanossi in preheated cups, sprinkle with parsley. Serve with rustic baguette.