
Make the fajita seasoning. Preheat oven to 425°F (220°C). In a small bowl, stir together the chili powder, cumin, garlic powder, paprika, oregano, salt, and pepper.
Season the chicken and veggies. Add the sliced chicken, sliced bell peppers, sliced onions, oil, and fajita seasoning mix to a large mixing bowl. Toss to combine.
Bake the chicken fajitas. Spread the seasoned chicken and veggies out on a rimmed baking sheet. Bake for 15 to 20 minutes, or until the chicken is cooked through.
Serve. Top a portion of the chicken fajitas on a tortilla and garnish with a squeeze of fresh lime juice plus your favorite toppings.