Whatever starch is used, it’s moistened first (if not actually still moist as part of the process of obtaining the starch from scratch), then forced through a machine that extrudes it out in noodles, with the fine strands going straight into warm water (around 100 F / 38 C) to cook them. Then they are rinsed with cold water, then hung and frozen to fully “retrograde” the starch, then rinsed one last time, and dried.
They are very thin, almost like hair, but not brittle. In fact, they can be somewhat hard to break up when dry.
They are sold dried in small bundles that on average are 1 1/2 to 3 oz (40 to 80g.)
When dry, they are translucent. When cooked, they become even more transparent (rice vermicelli in comparison is more opaque and whiter.) They also become soft and slippery, but slightly firmer still than rice vermicelli.
They have no flavour, but add texture and bulk and absorb other flavours in a dish.
They can be used in hot pots, salads, soups, stir-fries, and inside egg rolls. they are occasionally even used in sweet dishes.
Soak in hot water 10 to 15 minutes before using, except when you are using them in soups or frying. Stir once or twice while soaking to separate them, then drain and use. Or, simmer for 3 to 5 minutes, then drain. If using in a cold dish, refrigerate them afterwards to chill them. If you wish to heat them up after soaking for use with a sauce, simmer in boiling water for up to 3 minutes.
Add to soup when the soup is done; simmer until noodles are soft, then serve.
Glass Noodles can be fried from dried (without soaking in water first) to make crunchy toppings.
Called “pancit sotanghon” in Filipino, “su un” in Indonesian, “bun tau” in Vietnamese, “tanghoon” in Malaysia, “woon sen” in Thai.