Potato flour, is the pure starch that is leached out by soaking potato gratings in water. The liquid is drained off, leaving behind the starch, which is then dried. Similar to cornflour and used in the same way, potato flour needs only to be simmered gently for 1-2 minutes and should be added at the end of cooking; cook it any longer and the sauce will thin out again. It makes a good thickening agent and is better than cornflour for use in fruity or delicate sauces as it is both colorless and tasteless. It is usually available at good health food shops.
Rice flour is finely ground rice and is used in some Asian countries to make thin rice noodles. In common with potato flour, it thickens sauces and stews without flavoring or adding color to them, and is available in Asian food stores.
** Asian Recipes