 Spanish conquistadors brought potatoes and tomatoes from the Americas to Europe in the 16th century , but these vegetables only became commonly grown and consumed in Eastern Europe in the 19th century . Eventually , both became staples of peasant diet and essential ingredients of Ukrainian and Russian borscht . Potatoes replaced turnips in borscht recipes , and tomatoes – fresh , canned or paste – took over from beet sour as the source of tartness . The turnip is rarely found in modern recipes , and even then , together with potatoes . In Ukraine , beet sour and tomatoes were both used for some time until the latter ultimately prevailed during the last third of the 19th century . 
