
Make the salsa. Add the tomatillos, tomatoes, and jalapeños to a large baking sheet. Roast directly under the broiler for 10 minutes, flipping halfway through, until the veggies are charred and blistered. Add the garlic cloves to the baking sheet when only 1 minute remains, and the árbol chiles when only 30 seconds remain to avoid burning them.
Transfer everything to a large blender. Add the cilantro, salt, oregano, cumin, and broth. Pulse 5-10 times until mostly smooth. Set aside.
Make the tacos. Heat the oil in a large skillet over medium heat. Add the peppers and onions and sauté for 4-5 minutes until they start to soften.
Add the rotisserie chicken, fajita seasoning, and ⅓ cup of the blended salsa. Stir to combine and cook for an additional 3-4 minutes. Remove from the heat and set aside.
In a separate large skillet, heat enough oil to barely cover the bottom of the pan over medium heat.
Assemble the tacos by adding a spoonful of the rotisserie chicken mixture and some shredded cheese to one half of a flour tortilla. Fold the other half over, add it to the hot oil, and shallow-fry for 2 minutes per side until golden and crispy. Repeat the process with the remaining ingredients.
Serve the tacos with the remaining tomatillo salsa, a spoonful of sour cream, and some guacamole.