Bibim-naengmyeon (Spicy Mixed Cold Noodles)

Bibim-naengmyeon belongs to the noodle tradition of Hamheung in South Hamgyeong Province, now in North Korea. Food historian Joo Young-ha, in the folk encyclopedia, explains that the potato, a New World crop, reached Hamgyeong by way of northeastern China in the late Joseon period, and that noodles were pressed from its starch. Two inventions of the 1930s helped: in June 1932 Kim Gyu-hong, an ironworks owner in nearby Hamju, invented a metal noodle press, and in September 1933 the Sinheung railway line opened between Hamheung and the edge of the Gaema Plateau, whose potato farms then supplied the city's noodle houses. Locals called the result nongma-guksu, from their dialect word for starch. The Encyclopedia of Korean Culture describes the noodles as tougher than ox tendon.

Hamheung served these noodles two ways: in meat broth, and as hoe-guksu, dressed with raw fish. For the latter, the folk encyclopedia says, skinned flounder or pollock was cut thick, cured in vinegar, then seasoned with soy sauce, sugar, salt and chili and piled on noodles lightly dressed with sesame oil and soy. The Encyclopedia of Korean Culture notes that northerners generally ate little spicy food, yet this dish was unusually fiery. People in Hamgyeong simply called it noodles; the name "Hamheung naengmyeon" arose in contrast to the Pyongyang-style cold noodles fashionable under colonial rule.

After the Korean War, refugees from Hamgyeong clustered around Pil-dong and Ojang-dong in Seoul, and the name spread with their restaurants. Ingredients changed in the south: sweet potato starch, mixed with buckwheat flour, replaced potato starch, and skate (hongeo), cheaper and easier to find, replaced flounder. Joo stresses that the common southern shorthand — Pyongyang means broth noodles, Hamheung means spicy mixed noodles — is a misunderstanding, since Hamheung-style shops in the south have always served both. See northern provinces and noodles in Korean history.

• Fresh crunch: cucumber, pear and radish add water, potassium and texture to a cold summer meal. See boknal and summer foods.
• Chili: a large share of gochugaru supplies carotenoids (vitamin A activity) and capsaicin. See capsaicin and spicy food.
• Lean fish: flounder or skate adds lean protein and selenium with little fat.

• Hoe-naengmyeon (Seoul, Ojang-dong style): starch noodles with vinegar-cured raw skate in a fiery sauce; the folk encyclopedia says cheap skate was standard in southern Hamheung-style restaurants into the 1970s.
• Bibim-naengmyeon: the same noodles and sauce without raw fish, topped with sliced boiled beef or just egg, cucumber, pear and pickled radish.
• Hamheung nongma-guksu (northern provinces): the North Korean original, with the city's Sinheunggwan restaurant known for a version topped with pollock; in Hamheung itself the broth version uses a soybean-sesame soup, according to the Encyclopedia of Korean Culture.
• Busan milmyeon: Hamgyeong refugees in Busan blended relief wheat flour with sweet potato starch to make a noodle resembling their own, a dish known nationwide since the 2000s.