How to Make It
Heat broiler. Season the chicken with the chili powder and ¾ teaspoon salt. Place the chicken, tomatillos, onion, and jalapeño on a rimmed baking sheet. Broil, turning once, until the chicken is cooked through and the vegetables are charred and tender, 8 to 10 minutes.
Transfer the chicken to a plate to cool slightly. Using 2 forks, shred the chicken into large pieces.
Place the tomatillos, onion, jalapeño, and ¼ teaspoon salt in a blender. Process until a chunky salsa forms. Add the lime juice and cilantro and pulse to combine.
Top the tortillas with the chicken, salsa, and Cotija, and sprinkle with the extra cilantro, dividing evenly. Serve with the lime wedges.