Rassolnik is a traditional Russian

Russian cuisine

Russian cuisine is diverse, as Russia is the largest country in the world. Russian cuisine derives its varied character from the vast and multi-cultural expanse of Russia. Its foundations were laid by the peasant food of the rural population in an often harsh climate, with a combination of...

 soup made from pickled cucumber

Pickled cucumber

A pickled cucumber is a cucumber that has been pickled in a brine, vinegar, or other solution and left to ferment for a period of time, by either immersing the cucumbers in an acidic solution or through souring by lacto-fermentation.-Gherkin:A gherkin is not only...

s, pearl barley

Pearl barley

Pearl barley is barley processed to remove its hull and bran. Barley must have its fibrous outer hull removed before it can be eaten; pearl barley is taken a step further, polished to remove the nutritious bran layer....

 and pork or beef kidney

Kidney

The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...

s. A vegetarian variant of rassolnik also exists. The dish is known from the 15th century, when it was initially called kalya.

The key part of rassolnik is rassol, a liquid based on the juice of pickled cucumbers with some additions, famous for its usage in anti-hangover

Hangover

A hangover describes the sum of unpleasant physiological effects following heavy consumption of alcoholic beverages. The most commonly reported characteristics of a hangover include headache, nausea, sensitivity to light and noise, lethargy, dysphoria, diarrhea and thirst, typically after the...

treatment.