Quesadilla de Huitlacoche

Huitlacoche is a fungus that grows on corn. The galls swell on the ear during the rainy season in central Mexico, dark blue-grey at first, then black at the centre, the kernels distorted into soft lobes the size of a thumb joint. Aztec farmers ate them before the Spanish arrived; the Nahuatl name compounds cuitlatl (an excrescence or droppings) with cochi (a sleep). Modern Mexican kitchens cook the galls down with onion, garlic, and epazote until the whole mass reduces into a soft inky stew the colour of wet ash and the texture of damp earth, with a flavour somewhere between mushroom, corn silk, and forest floor. The cook folds a spoonful of that reduction into a fresh corn tortilla with a melting cheese, holds the closed fold on a hot comal until the dairy binds the masa shut, and serves it to be eaten with the fingers from a paper plate.

The cheese is the small move that lifts this build from a smear of cooked fungus inside a folded tortilla into a proper quesadilla. The galls on their own are intensely savoury, slightly bitter, low in fat, and high in moisture; folded into a tortilla without anything to carry them, they slide apart and read as a powerful smear with no anchor. A controlled layer of quesillo or asadero melts in between the filling and the masa, supplies the fat the fungus lacks, rounds the bitter edge, binds the loose black core to the tortilla, and pulls in pale ropes when the seam is opened. The dairy is doing the same work it does in any folded build; what is unusual is what it has been asked to carry.

The cooking discipline is mostly about the moisture. Fresh huitlacoche releases a black inky liquid as it cooks, and a filling left under-reduced floods the masa, refuses to seal, and weeps grey-black water out of the fold the moment the cook lifts it off the steel. The standard preparation sweats finely chopped white onion and a little garlic in oil first, adds the chopped galls with a sprig of epazote, and reduces over moderate heat for ten to fifteen minutes until the mass has darkened, thickened, and dropped almost all its visible liquid. Epazote is the structural seasoning here: its sharp acrid leaf cuts through the depth of the fungus and keeps the bite from going flat under its own earthiness. Salt is added late, since the filling concentrates with reduction and an early salt over-seasons by the end. A bite from a well-built fold is dark, dense, faintly bitter, savoury well past where the dairy flavour ends, the epazote arriving as a small medicinal sharpness near the back of the chew.

The tortilla is the structural hinge. A fresh nixtamalized corn sheet, pressed and cooked moments before the fold, stays pliable enough to take the wet filling and toast enough on the comal to develop dark freckles on the outside while the cheese fuses the interior. A day-old tortilla reheated from a stack cracks at the fold and refuses to seal, and the filling escapes the moment the customer picks it up. A sheet pressed too thin tears under the weight of the reduced galls; pressed too thick, it cooks slowly and the cheese sets cold before the masa toasts. The cook works fast, keeps the comal hot but not scorching, and turns each fold once.

The smell off the comal is the first signal. Lift the fold and the aroma is damp earth, leaf litter after rain, and something faintly metallic underneath, with the corn toast of the masa as the dry note above it; the outside of the fold is freckled black and brown where it met the iron and the dairy has crisped at the rim. The first bite gives a crisp masa edge, then a long pull of stretched white cheese, then the inky core arrives in a wave with the epazote riding on top. The temperature is uneven across the bite, the outer masa hot, the cheese hotter, the fungus reduction the warmest core; the colour on the plate when the seam is broken open is unmistakable, the white of the dairy stained grey-black at every interface. The aftertaste is dark and lingers, less mushroom than the eater expects and more vegetal-mineral than that.

The ordering language is shorter than for most quesadilla fillings because the season does most of the asking. Una quesadilla de huitlacoche, possibly con queso in Mexico City where the cheese-versus-no-cheese argument runs through every quesadilla order, is the standard call at a market fonda or a Roma Norte mid-range restaurant; in season the cook produces it from a fresh reduction made that morning, out of season she ladles it from a tub of preserved or canned product kept in the refrigerator. The peak fresh season runs from June through September on the central Mexican harvest calendar; the rest of the year a canned or jarred fungus carries the dish, with the texture flatter and the depth a register narrower than the fresh.

Variation is mostly seasonal and regional. Fresh galls from a State of Mexico or Tlaxcala milpa, eaten within a day of harvest, are brighter and more delicate than canned and produce a quesadilla that reads of corn silk and damp soil at once; canned product from a national-brand jar makes a flatter, more uniformly savoury filling that holds up well as a winter or restaurant menu item. Chefs in Mexico City sometimes finish the filling with a small spoonful of cream for additional fat, or fold in sautéed squash blossoms (flor de calabaza) for a paler, more floral version that is its own seasonal item. The fungus also turns up in tamales, in soup, in pasta sauces at modern Mexico City kitchens, and as a filling for empanadas; each is a different dish, not a quesadilla variant.

Huitlacoche and the Aztec corn fungus

The fungus is Ustilago maydis, a plant pathogen that infects developing corn ears worldwide; in most of the world maize farmers consider it a crop disease and call it corn smut, which the United States Department of Agriculture has historically advised growers to control or destroy. In central Mexico the same growth is harvested as a delicacy and has been eaten since at least pre-Hispanic times. The Nahuatl name cuitlacochi, anglicised as huitlacoche, is recorded in Aztec ethnobotanical sources collected by the sixteenth-century Spanish Franciscan friar Bernardino de Sahagún, whose Historia general de las cosas de Nueva España (the Florentine Codex), compiled with Nahua informants between 1545 and 1590, lists it among the edible plants of the Valley of Mexico.

The English-language popularisation of the ingredient runs through Diana Kennedy. Her landmark Mexican-cookery survey was released by Harper & Row in New York in 1972 and introduced English-language readers to huitlacoche in central-Mexican home cookery, recording the quesadilla and other standard preparations. Kennedy and the broader generation of writers around her (including Patricia Quintana, and later Rick Bayless on the American side) translated huitlacoche as “Mexican truffle” for non-Mexican audiences, a calque that pulled the ingredient onto American restaurant menus through the 1980s and 1990s as the upscale-Mexican fine-dining movement built its national profile.

Bernardino de Sahagún compiled the Florentine Codex with Nahua informants between 1545 and 1590, and the work lists cuitlacochi by name as a foodstuff among the Aztecs of the Valley of Mexico.