Sweet potato flour/powder (地瓜粉) is used in many culture's cusines, including South American. It can be made from either white or more orange colored sweet potatoes, with most Taiwanese being made from white sweet potatoes.
Where to Buy
Most Asian grocery stores, Latin American grocery stores, or even your local American super market depending on your location.
Buy at Amazon and support this site: Sweet Potato Flour - 16oz.