Place a rack in the center of the oven and heat to 425°F (220°C). Line a large rimmed sheet pan with parchment paper or foil.
In a small bowl, mix the chili powder, cumin, smoked paprika, garlic powder, onion powder, oregano, salt, and pepper.
In a large bowl, combine the chicken, peppers, and onion. Add the olive oil, lime juice, and seasoning, and toss until evenly coated.
Spread the mixture in a single layer on the prepared pan, leaving a little space between pieces.
Roast for 18 to 22 minutes, stirring once halfway through, until the chicken reaches 165°F (74°C) and the vegetables are tender with browned edges.
For extra color, broil for 2 minutes, watching closely.
Warm the tortillas in a dry skillet or wrapped in foil in the oven.
Serve the fajita mixture in tortillas with avocado, salsa, yogurt or sour cream, cilantro, and lime wedges.