Pickles and pickle juice form the cornerstone of a traditional Russian soup called rassolnik, a recipe reputed to have hangover-curing properties. Though vegetarian styles are made, the classic way of preparing this six-centuries-old dish is with the kidneys of either pigs or cows, or just some chicken livers. Along the way, other more universally accepted soup ingredients are often added, like potatoes, carrots, onions, barley, chicken breast chunks and a medley of herbs.
Once known as kalya, rossolnik evolved as a Russian way to feature a favorite of local cuisine — the pickled cucumber. To prepare the dish, most chefs start by making a stock, usually by boiling the bones of whatever meat will be used with some onion, garlic, bay leaf, salt and pepper, then straining the liquid. Others just buy chicken, beef or vegetable stock.
Cooking the kidneys for the rassolnik takes precision and care, or else the organs' toxicity could be transferred to the dish. This means boiling the whole, fat-trimmed kidneys in water for about 10 minutes or more, then throwing away the water. The kidneys are then simmered for another hour in a fresh pot of water, and then that water can be added to the stock to blend the flavors, while the kidneys are sliced into small chunks.
As the kidneys are cooking, many chefs start preparing the remaining ingredients for the rassolnik. Chopped vegetables like carrots, more onions, celery and potatoes are "sweated" in a pan, then added to the stock. Barley is frequently added too at this point.
The pickles come nearly last in preparing rassolnik. They are peeled, cut into small cubes, and sweated in the same pan as the other vegetables. Just when the potatoes are ready to eat, the pickles are added to the soup, along with herbs like coriander, cilantro, thyme and parsley. Left in the stock for too long, these ingredients become devoid of any flavor.
As with another popular Russian soup, the cabbage-centric shchi, rassolnik is often garnished with sour cream and some chopped dill, which complement the sour pickle flavoring. Some make the soup more sour by soaking the pickle peelings in some boiled water for about 10 minutes and then adding this liquid to the stock. Another tweak on the original recipe involves using pieces of chicken or beef instead of the usual kidneys or gizzards, or leaving out all meat and making the pickles the one and only star.