Huitlacoche (also spelt cuitlacoche) is the edible corn smut — the plump, silver-grey to blue-black GALLS that the fungus Ustilago maydis grows in place of ordinary kernels on the developing ear of maize. Prized in Mexico as a delicacy and marketed abroad as the "Mexican truffle," it is one of the few plant diseases deliberately cultivated to eat: swollen, mushroomy and inky, with a deep earthy-sweet, smoky-savoury flavour that tastes of both corn and mushroom at once. It is always eaten cooked.