 Most often , borscht is dished up with sour cream , the East European version of which , known as smetana , is <unk> than its American counterpart . The sour cream may be served in a separate pitcher for the diners to add the desired amount themselves or the borscht may come already " whitened " , that is , blended with sour cream . Sometimes the cream is thickened with flour before being added to the soup . Yogurt and a mixture of milk and yolks are possible substitutes . 
