By Harold McGee
These are all names for the elongated root of a tropical plant in the spurge family, Manihot esculenta, which has the very useful habit of lasting in the ground for as much as three years. It was domesticated in northern South America, and has spread through the lowland tropics of Africa and Asia in the last century or so. It’s often made into flatbreads or fermented as well as cooked on its own. There are two general groups of cassava varieties: potentially toxic “bitter” varieties that are used in the producing countries, and safer “sweet” varieties that are exported and found in our ethnic markets. Bitter varieties, which are highly productive crop plants, have defensive cells that generate bitter cyanide throughout the root, and must be thoroughly treated—for example, by shredding, pressing, and washing—to become safe and palatable. They’re mainly processed in the producing countries into flour and tapioca, small balls of dried cassava starch that become pleasantly jelly-like when remoistened in desserts and drinks. Sweet cassava varieties are less productive crop plants, but have cyanide defenses only near their surface, and are safe to eat after peeling and normal cooking. The root flesh is snow-white and dense, with a bark-like skin and a fibrous core usually removed before cooking. Cassava benefits from cooking in water to moisten the starch before being fried or baked.