Japanese Harusame and Glass Noodle Culture: Mung Bean and Potato Starch Preparations
Japan — Chinese origin (fen si), adapted into Japanese cuisine tradition
Harusame (春雨 — spring rain) — glass noodles made from mung bean starch or potato starch — occupy a specific textural niche in Japanese cuisine that is distinct from wheat noodles (soba, udon, somen) and rice noodles: they become translucent when cooked, have a slippery, yielding texture with a characteristic 'spring rain' delicacy, absorb surrounding flavours readily, and are used in both hot preparations (nabe, hotpot, soups) and cold preparations (salads, dressed dishes). Japanese harusame are typically made from potato starch or sweet potato starch (distinct from the mung bean glass noodles common in Chinese and Korean cuisines, which are thicker and firmer). The Japanese potato starch harusame are thinner and more delicate, cooking to translucency in minutes. In nimono (simmered dishes), harusame added to the pot absorb dashi and soy to become intensely flavoured while providing a textural bridge between firm vegetables and soft proteins. In salads (harusame salad — a popular izakaya preparation), cooked and cooled harusame are dressed with rice vinegar, sesame oil, soy sauce, sugar, and various vegetables (cucumber, carrot, ham, wood ear mushroom) — the dressing clings to the smooth noodle surface, creating a refreshing summer dish. In hotpot, harusame absorb the complex broth as the meal progresses, becoming a deeply flavoured reward at the end of the bowl. Unlike Korean dangmyeon (thicker sweet potato glass noodles used in japchae), Japanese harusame are too delicate for stir-frying — they are best suited to simmering, cold salads, and as a final addition to hotpots.