Shchi
Shchi is a Russian-style cabbage soup. When sauerkraut is used instead, the soup is called sour shchi, while soups based on sorrel, spinach, nettle, and similar plants are called green shchi (Russian: зелёные щи, IPA: [zʲɪˈlʲɵnɨje ɕːi]). In the past, the term sour shchi was also used to refer to a drink, a variation of kvass, which was unrelated to the soup. Shchi (from Old East Slavic: съти, the plural of "съто" (s(i)to) – "something satisfying, feed") is a traditional soup of Russia. Cabbage soups have been known in Kievan Rus as far back as the 9th century, soon after cabbage was introduced from Byzantium. Its popularity in Russia originates from several factors: As a result, by the 10th century shchi became a staple food of Russia, and a popular saying sprang from this fact: "Щи и каша — пища наша." (Shchi e kasha — pishcha nasha "Shchi and kasha are our food").
Source: Wikipedia