Rice flour
Finely milled flour from glutinous rice that turns chewy, elastic and sticky when cooked.
Glutinous rice flour is milled from glutinous rice, a variety especially high in sticky starch; despite the name it contains no gluten. Cooked, it becomes chewy, stretchy and springy, and that texture is what carries Korean rice cakes, filled pancakes and the paste used to bind kimchi seasoning. It should not be confused with plain rice flour, which stays soft and rather crumbly when cooked. It is sold in Asian grocery shops, often labelled glutinous rice flour or sweet rice flour although it does not taste sweet, and by mail order.
Substitute:
For thickening kimchi seasoning paste, plain rice flour or a little wheat flour will do, the paste is just slightly less smooth. For rice cakes and anything meant to be chewy and stretchy there is no substitute, since neither plain rice flour nor wheat flour or cornstarch achieves that texture.