Short of investing in a vertical broiler, this hack is the closest you’ll get to al pastor tacos at home.
New Mexican or Anaheim chiles can be substituted for the guajillo chiles. If queso fresco is unavailable, you can substitute farmer's cheese or a mild feta. When baking the tortillas, stir them well to promote even browning.
This recipe is old-fashioned in the sense that it doesn't involve any canned milk, powders, or artificial flavorings. It results in a flan that is not too eggy thanks to the use half-and-half instead of milk to help thicken it.