 Borscht also evolved into a variety of sour soups to the east of Poland . Examples include onion borscht , a recipe for which was included in a 1905 Russian cookbook , and sorrel @-@ based green borscht , which is still a popular summer soup in Ukraine and Russia . A Gift to Young Housewives by Elena Molokhovets , the best @-@ selling Russian cookbook of the 19th century , first published in 1861 , contains nine recipes for borscht , some of which are based on kvass , a traditional Slavic fermented beverage made from rye bread . Kvass @-@ based variants were also known in Ukraine at that time ; some of them were types of green borscht , while others were similar to the Russian okroshka . 
