Roots soup are cleared and washed and together with the onion, cut into halves, bay leaves, grains pepper, allspice, vinegar and salt to boil in a small mixing water. Then add the cleaned, cut into pieces of fish. Allow to boil and dovaryava 10-20 minutes on low heat (not boil). Of butter and flour make a light roux, which is made up with 2 cups strained fish broth. Add sour cream and chopped dill, seasoned with sugar, pepper, vinegar and horseradish. After removing from the fire, add the egg yolks and parsley. Thick sauce is poured on a warm fish and served with boiled potatoes.