해장국 (Haejang-guk), aka “Hangover Soup,” is a hearty stew served across Korea. I ordered it by random, assuming that the hae referred to “seafood,” but my error was a pleasant mistake. Honestly, it seems a lot like any other soup in Korea, although the addition of a chunk of bone and the coagulated blood are nice touches that should provide valuable nutrients.
국 (guk) is a word meaning soup, and 해장 (haejang) does literally mean “to get sober,” so the nickname is a proper translation.
I can attest to having it in the middle of a drinking session and not having a hangover the next day, though I wasn’t drinking that much to begin with. Worth a try, but I wouldn’t want it if I actually had a hangover.