1
Toss the chicken, red onion, and bell peppers with the olive oil, lime juice, and fajita seasoning and marinate for up to 30 minutes. This step can be skipped if you are short on time.
2
Preheat the oven to 400 degrees. Spray a baking sheet with cooking spray. You can also cover it with foil for easier cleanup. Spread the chicken and vegetables in a single layer on the baking sheet in a single layer.