Peel carrots and celery and cut into small pieces. Clean the white cabbage and leek, wash them thoroughly and cut them into small pieces as well.
Put the chopped vegetables in a large pot and fill with water until everything is covered. Bring to a boil and simmer for about 30 minutes.
Finely chop parsley, add to vegetables and season soup with vegetable soup cubes.
Simmer again for 5-10 minutes, then serve.