Rice flour
Finely ground rice, gluten-free, used for batters, flatbreads and thickening.
Rice flour is sold in Asian grocers, health food shops and increasingly in supermarkets alongside gluten-free products. Use ordinary rice flour, not glutinous rice flour, which cooks up chewy and sticky.
Substitute:
In a pinch, you can grind rice finely yourself in a high-speed blender or spice grinder. Wheat flour makes batters chewier and less crisp, and it is not gluten-free.