I spent a year living in Mexico City in the mid 90s. I fell in love with the Quesadillas at a Mercado in Coyoacán located on Higuera just behind the main church and the plaza Jardin Hidalgo. I ate these quesadillas at least once per week–but oftentimes two or three times per week.
To be clear, there are about a dozen or so individual food stalls inside this market. You’ll find pozole, huaraches, pambazos, and a slew of other tasty, and authentic, street food. My favorite, though, hands down, are the amazingly delicious quesadillas sold at one particular stall. In fact, I’ve been eating quesadillas from this same stall since 1995. Any visit to CDMX is never complete without a visit to Coyoacán and a couple of these quesadillas. For myself, anyhow.
Now, when Americans think of quesadillas, they typically think flour tortillas and cheese. But these quesadillas are Mexico City style. In fact, surprise surprise, one can get a quesadilla with no cheese whatsoever. These quesadillas, with or without cheese, are filled with a myriad number of other tasty fillings: picadillo (ground beef), hongos (mushrooms), rajas (peppers), chorizo, pollo, huitlacoche (corn smut), flor de calabaza, chicharron (pork rinds), etc. These fillings are layered thick on a freshly made maize tortilla, the maize is quickly folded over to make it taco shaped, and it’s thrown into a very large wok style fryer filled with hot oil. I always go with picadillo, hongos, and/or rajas. And of course, I always add cheese. So tasty.
Find a seat on one of the long wooden beaches situated around the 2-3 person operation. Grab or ask for one of the handy writing pads and jot down your order. And watch the woman go at it. It’s always an impressive sight.

Below: My quesadilla de rajas con queso. Love them! Notice the hole right in the middle of the quesadilla. The woman working the fryer, a second after removing the quesadilla from the hot fryer, quickly pokes a hole in the quesadilla to determine the filling.

I always add some green chile (salsa) to my quesadillas. Finger licking good.

So if you’re looking for a cheap yet amazingly tasty lunch while in Coyoacán, head to the Mercado de Antojitos Mexicanos Juanita, look for the busiest stall that sells quesadillas, and enjoy!
Mercado de Antojitos Mexicanos
Higuera 10
Coyoacán