Clean and peel the carrots, onions, leeks and celery and then cut very finely. Add the water with the stock powder.
Gently heat the butter or margarine in a saucepan and sauté the chopped vegetables in it. Season to taste with salt, pepper and broth and boil in water for about 15 minutes. Thicken the soup with crème fraîche, wine and flour. Season again to taste, then refine with parsley or any other ingredient.