 Ashkenazi Jews living in Eastern Europe adopted beetroot borscht from their Slavic neighbors and adapted it to their taste and religious requirements . As combining meat with milk is proscribed by kosher dietary laws , Jews have developed two variants of the soup : meat ( <unk> ) and dairy ( <unk> ) . The meat variant is typically made from beef brisket ( pork is never used ) and cabbage , while the dairy one is vegetarian , blended with sour cream or a mixture of milk and egg yolks . Both variants typically contain beetroots and onions , and are flavored with beet sour , vinegar or citric acid for tartness and beet sugar for sweetness . Galician Jews traditionally liked their borscht particularly sweet . Jewish borscht may be served either hot or cold , typically with a hot boiled potato on the side . In prewar Eastern Europe it was traditionally put up to ferment around Purim so that it would be ready four weeks later for the Passover holiday . 
