naengmyeon noodles
Thin, greyish Korean noodles made from buckwheat flour and starch, strikingly chewy and elastic, used mainly for cold noodle dishes.
Naengmyeon noodles are thin Korean noodles made from buckwheat flour mixed with sweet potato or potato starch and often a little wheat flour. Their texture is what matters: they are much chewier and more rubbery than Japanese soba, almost springy, with only a faint nutty buckwheat flavour. The chewiness is intended, which is why the noodles are often cut with scissors at the table in Korea. They cook in just a few minutes and are then rinsed thoroughly in cold water to remove surface starch and keep them firm. They are sold dried or chilled in Asian grocery stores, frequently packed together with broth and sauce sachets, and through online retailers.
Substitute:
There is no truly good substitute, because the characteristic chewiness comes from the starch. Japanese soba match the buckwheat flavour but are soft and break easily; Korean sweet potato glass noodles have the chewiness but neither the colour nor the taste. In a pinch, use thin soba and expect a noticeably softer dish.