There's not a lot of detailed information in English on salgam suyu, a juice made from pickled purple carrots and fermented bulgur that's popular in southern Turkey. So if you depended on the Google translation of its Turkish Wikipedia page, you might stay away:
"Ornamental pepper pickled turnips bitter juice is used as the often painful. Taste than 1/3 to 1/6 rate turnips join. But the pain of rape should not be stored after mixing more, turnips deteriorate."
Istanbulfood's post is much more encouraging: cooked red carrots, turnips, and fermented wheat go in a wooden barrel. Salt is added, maybe some chili (the pain source), where it stews for a while, before filtering. I spent a month in Turkey and I never came across the stuff, but apparently it's drunk cold with a red carrot swizzle, as a digestif, hangover cure, or an accompaniment to kebabs, cig kofte, and/or raki. Sour, salty, and spicy, it has the same seemingly counterintuitive refreshment powers as Vietnamese salty limeade.
It showed up recently at Sahar Meat Market (along with a full service shawerma counter), perhaps in anticipation of a sweltering summer. It's available "painful and painless."
Sahar Meat Market, 4829 N. Kedzie, 773-583-6098