Prep the Chicken
Pull all the meat and skin off the rotisserie chicken. Shred it into bite-sized pieces. Don’t discard the skin chopping it up adds great texture and flavor.

Cook the Filling
Preheat a large griddle or cast-iron skillet to medium heat. Drizzle with avocado oil. Add the shredded chicken, green chiles, and pickled jalapeños. Sprinkle generously with taco (or fajita) seasoning. Cook for 5 minutes, tossing frequently to crisp up the meat.

Melt and Crisp
Add the diced tomato and shredded Pepper Jack cheese to the chicken mixture on the griddle. Stir to combine. Crucial Step: Let the cheese hit the hot surface directly. Allow it to melt and get golden brown and crispy in spots (this crispy cheese is called “frico” or “costra”).

Toast the Bread
While the filling finishes, slice the bolillo rolls open. Slather mayonnaise on the cut sides. Place them mayo-side down on the hot griddle. Toast for 2 minutes until golden brown, then flip briefly to warm the outside.

Assemble
Use a spatula to scoop the hot, cheesy chicken mixture onto the bottom halves of the toasted rolls.

Top and Serve
Top the hot filling with the cool, shredded iceberg lettuce, chopped cilantro, and diced onions. Close the sandwich with the top bun, slice in half, and serve immediately.