Most butchers will remove the backbone for you.
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.
Greens, avocado, tomato and red onion are sprinkled liberally with the chaat masala and a little fresh chile. Layer cooked chicken breast on top and drizzle the whole thing with a cumin-coriander based dressing.