Sweet potato glass noodles

Dangmyeon are glass noodles made from starch — in Korea most often sweet potato starch, sometimes blended with potato starch. Dry, they are gray and brittle; cooked, they turn glossy, springy and nearly transparent. The name means 'Chinese noodles,' and they were also once called homyeon.

The noodles came to Korea from Qing China in the late Joseon period. Large-scale production began in 1919, when a Korean entrepreneur, Yang Jae-ha, built a dangmyeon factory in Sariwon, Hwanghae Province, reportedly big enough to export to Japan.

Factory-made noodles changed Korean cooking. Japchae in Joseon-era cookbooks was a dish of shredded, stir-fried vegetables and mushrooms with no noodles at all; dangmyeon entered the recipe during the colonial period and appears as a japchae ingredient in cookbooks from 1934 onward. To make the noodles, part of the starch is cooked into a paste, kneaded with the rest and warm water, pressed through a perforated mold into boiling water, then cooled, frozen, thawed and sun-dried.

Beyond japchae, dangmyeon holds its chew in hot pots and stews, fills fried seaweed rolls (gimmari), bulks up jjimdak, and stars in Busan's bibim-dangmyeon, a market snack of noodles tossed with spicy sauce.

• Mostly starch: Dangmyeon is essentially pure carbohydrate with almost no protein or fat, so its nutritional value comes from what it is cooked with — in japchae, the vegetables, mushrooms and meat.
• Naturally wheat-free: Pure sweet potato starch noodles contain no wheat, but recipes vary by brand, so people avoiding gluten should check the ingredient list.
• Portion and seasoning: Because the noodles absorb soy sauce and oil readily, dishes like japchae can be richer in sodium and fat than the plain noodles suggest.