Heat the oven to 450°F (230°C) with a rack in the upper third. Line a large rimmed baking sheet with foil or parchment.
In a large bowl, whisk the oil, lime juice, chili powder, cumin, paprika, garlic powder, oregano and salt.
Add the chicken, peppers and onion and toss until everything is evenly coated.
Spread the mixture in a single layer across the pan, using two pans if it is crowded.
Roast for 18–22 minutes, stirring once halfway, until the chicken is cooked through and the vegetables are tender with charred edges. For extra color, broil for the last 2 minutes.
Squeeze a lime wedge over the pan and serve with warm tortillas and your choice of toppings.