Tiger nuts, one of the hottest superfoods on the market, are not, in fact, nuts. These wrinkled, marble-sized orbs are small, tuberous rhizomes of a sedge grass (cyperus esculentus lativum) that's been cultivated for millennia around the world. Native Americans enjoyed tiger nuts, as did the ancient Egyptians. In Spain, where they're known as chufa, they're the traditional ingredient for horchata.With a flavor reminiscent of both coconut and almond,...