tapioca starch

        In the harsh climate and thin soil of the world's tropical regions, starchy, sustaining foods such as potatoes and grains often grow poorly. The staple crop in these regions is manioc, or cassava, a plant producing edible green leaves and large, starch-rich tubers. Some varieties contain lethal amounts of cyanide that must be cooked out, leaving a dry and nutritious flour. When that flour is further processed into a pure starch, the result is tapioca. It's most commonly sold in small balls, or pearls, and cooked into pudding, but the pure starch is also a potent thickener.