Preheat your oven to 400°F (200°C). Line a large rimmed baking sheet with parchment paper for easier cleanup.
In a large bowl, combine the sliced chicken, peppers, and onion.
In a small bowl, whisk together the olive oil, chili powder, cumin, smoked paprika, garlic powder, oregano, cayenne pepper (if using), salt, and black pepper to create the seasoning blend.
Pour the seasoning mixture over the chicken and vegetables. Toss everything together until the chicken and vegetables are evenly coated.
Spread the seasoned chicken and vegetables in a single layer on the prepared baking sheet. Do not overcrowd the pan; use two pans if necessary to ensure proper roasting, not steaming.
Bake for 18 to 22 minutes, or until the chicken is cooked through (internal temperature reaches 165°F or 74°C) and the vegetables are tender-crisp.
Remove the pan from the oven. Squeeze the fresh lime juice over the hot chicken and vegetables and toss gently on the pan.
Serve immediately with warm tortillas and your choice of toppings.
Notes
For best results and to avoid soggy vegetables, slice the vegetables uniformly and ensure they are in a single layer on the pan.
To keep the chicken tender, do not overcook it; check the internal temperature near the 18-minute mark.
If you prefer a skillet method, cook the chicken first until almost done, remove it, then cook the vegetables until tender, and finally return the chicken to the pan to finish cooking together.