Ленинградский рассольник с почками. Leningrad rassolnik with kidneys

Rassolnik is a traditional Russian soup made from pickled cucumbers, pearl barley, and pork or beef kidneys. This version is called Leningrad rassolnik because it is made with beef kidneys. A vegetarian variant of rassolnik also exists, usually made during Lent. The dish is known to have existed as far back as the 15th century, when it was called kalya. Rassolnik became part of the common Soviet cuisine and today it is also popular in Ukraine and Belarus. A similar dish is common in Poland, where it is known as zupa ogórkowa (literally cucumber soup).