Shiratamako Flour  Shiratamako Flour is a version of sweet rice
flour, milled by wet-meal-method. It is more expensive than
mochiko.  To make it, grains of sticky rice are first soaked in
water, then the soft rice is mashed, then freeze dried.  The
flour is lumpy, even though the size of the powder grains is
actually very fine. Some people like to whiz it in a blender
before using to make it a fine powder.  When cooked, it creates
a very fine texture. It also makes doughs come out both very
stretchy, and sticky.   Substitute: per half cup of mochiko, add
1 tbsp of cornstarch or potato starch.  Language Notes
Shiratamako means "white jade powder."