Chop the onion very thin rings and fry in preheated lard, add salt and stew on low heat sandwiching court until choke and turn yellow. Pour 1.2 liters of cold water, gradually vazvaryava on low heat and boil 10 minutes. Yolks mixed with vinegar and a little broth, pour gradually into the soup and the soup is heated, but not boiling. In each plate place 2 slices of toasted bread and pour soup.