 It may never be known who first thought of using beet sour to flavor borscht , which also gave the soup its now @-@ familiar red color . Jerzy Samuel Bandtkie 's Polish @-@ German dictionary published in 1806 was the first to define barszcz as a tart soup made from pickled beetroots . The fact that certain 19th @-@ century Russian and Polish cookbooks , such as Handbook of the Experienced Russian Housewife ( 1842 ) by Yekaterina Avdeyeva and The Lithuanian Cook ( 1854 ) by Wincenta Zawadzka , refer to beetroot @-@ based borscht as " Little Russian borscht " ( where " Little Russian " is a term used at the time for ethnic Ukrainians under imperial Russian rule ) suggests that this innovation took place in what is now Ukraine , whose soils and climate are particularly well suited to beet cultivation . Ukrainian legends , probably of 19th @-@ century origin , attribute the invention of beetroot borscht either to Zaporozhian Cossacks , serving in the Polish army , on their way to break the siege of Vienna in 1683 , or to Don Cossacks , serving in the Russian army , while laying siege to Azov in 1695 . 
