Welcome to the world of Mexican corn smut, better known as h(c)uitlacoche.
What is huitlacoche?
Also called corn mushroom, Aztec caviar or Mexican truffle, it’s a fungus that the Aztecs knew about; the name derives from the Náhuatl words cuitlatl, or droppings, and cochi, sleeping. The corn kernels become entirely consumed by the fungal disease, swell, turn grayish and surprisingly, wind up in your street food; when the huitlacoche is still white, you can eat raw, but if it has already turned gray/black, it should be cooked. It doesn’t ordinarily devastate whole corn crops at one time, so a visit to a cornfield might take you a while to find husks that are infected.
In Mexico, huitlacoche is lauded for its nutrients – it is low in fat and high in fiber and antioxidants – and health benefits, but in the USA, you’re more likely to see it canned in Mexican supermarkets.
I first tried huitlacoche in Cancun, Mexico; the flavor was earthy and nutty, and even a bit salty, though that may have been due to the melted quesillo (Oaxaca cheese). It is normally found at the height of the Mexican rainy season, in July and August, but given its popularity, some agronomists are experimenting with growing the Ustiligo maydis fungus year-round.