This recipe for polish christmas eve beet soup (barszcz wigilijny) is from chef marek (mark) widomski, founder and director of the culinary institute in crakow, poland. While many beet soup recipes call for beef stock, meat or bones, since this is a polish christmas eve supper (wigilia) recipe, it must be meatless. The soup is made with a beet sour (kwas) that must ferment for at least three days before using and vegetable stock. The traditional way to eat barszcz wigilijny is with mushroom uszka or paszteciki. At the culinary institute in crakow, chef mark and his staff offer classes in everything from peasant food to gourmet cuisine, tailoring them to the individual's needs, in polish, english and other languages.