Tequesquite or tequezquite

Tequesquite or tequezquite is an ancient ingredient that is important to this day in Mexico, though it is not quite reproducible here. It is a mixture of alkaline salts that is collected from lake beds during the dry season. Dissolved in water, it makes agua de tequesquite. The indigenous Mexicans used it as an equivalent of regular salt, and for other culinary purposes that still persevere in parts of Mexico. It serves as a leavener in place of commercial baking soda or baking powder. In some areas it is considered essential for giving corn masa and other doughs a light, fluffy texture. It is also used in vegetable cookery, as some U.S. cooks would use a pinch of baking soda—for example, to soften dried beans, and to retain the natural color of nopales and other vegetables.