Potatoes, diced, leeks, chopped, carrots, sliced, pour 6 cups hot salted water and boiled, and then through a sieve, and again put in the broth. Flour stew in vegetable oil until golden coloring and added into boiling soup. After 15-20 minutes, add the butter. Then immediately remove the soup from the heat and sprinkle with chopped parsley. Serve hot.