So the other night I was reading this cool open-access research paper on the ethnobotany of Belarus. As you might expect, (1) Belarusians in the 19th Century made a lot of things into soup! and (2) many of these older wild food traditions have died out, particularly when it comes to wild greens.
Anyway, one of the wild green culinary traditions that’s still thriving in modern Belarus is the use of Rumex species to make a sour soup. Rumex is a large genus, including various kinds of docks and sorrels. The paper didn’t mention which species in particular were most popular (other than the modern adoption of R. confertus, a non-native species) but did mention that the sourness came from the greens, as opposed to other traditional sour soups where the souring agent is a lactic acid fermentation. And the Internet quickly yielded a recipe and a name: Chaladnik. Then more names – apparently this soup is more commonly known as schav and it is a part of cuisines throughout Eastern Europe. Why was I not informed?
I ignored the more-bitter less-sour broad-leaf dock (Rumex obtusifolius) in my backyard in favor of the sheep sorrel (R. acetosella), and threw in some wood sorrel (Oxalis somethin or other) since it is soured by the same chemical. (Oxalic acid, by the way, will give you kidney stones if you eat too much of it. It’s present in moderate concentrations in many common foods like rhubarb, purslane, and spinach, all of which I adore, because oxalic acid is the most delicious kidney stones ever.)