Tapioca flour or starch (paeng mun sam Palang in Thai) is used in Thailand for candy coating for frying foods, and as a thickener.
Tapioca flour is made from the yucca or cassava root (originating from South America) it is also the glue that egg roll together. The root as raw toxic parts of hydrogen cyanide or hydrocyanic acid, but after the juice is squeezed out and the tuber pounded to a paste and cooked, it's edible. Tapioca flour is made from this paste.
Tapioca flour or starch is used in Thailand for both candy, and for the dry-coated food frying. In preparation of a glossy clear sauce 1 part tapioca flour to be added to 1-2 volumes of water. For use as a thickening agent, mix well with a little water before adding to your dish, so it does not suddenly.