Preheat the oven: Set your oven to 375°F so it's hot and ready when your fajitas are assembled.
Season the chicken: In a large bowl, combine diced chicken, olive oil, paprika, garlic powder, onion powder, chili powder, dried oregano, cumin, salt, and black pepper. Toss until the chicken is well-coated.
1 ½ pounds chicken, 1 red onion, ½ teaspoon paprika, ½ teaspoon garlic powder, ½ teaspoon chili powder, ½ teaspoon dried oregano, ½ teaspoon cumin, 1 teaspoon salt, 1 teaspoon black pepper, 2 tablespoon olive oil, ½ teaspoon onion powder
Add veggies: Add the minced garlic, sliced red, yellow, and orange bell peppers, and sliced red onion. Mix everything until evenly coated.
1 red bell pepper, 1 yellow bell pepper, 1 orange bell pepper, 2 garlic cloves, 1 red onion
Prepare the sheet pan: Line a sheet pan with parchment paper or lightly grease it. Spread the seasoned chicken and veggies evenly in a single layer across the pan to ensure even cooking.
Bake the fajitas: Place the sheet pan in the oven and bake for 30-35 minutes, or until the chicken is fully cooked and lightly browned. Stir halfway through to ensure even cooking. Check the chicken for doneness before removing it from the oven.
Warm the tortillas: While the fajitas bake, warm your tortillas according to the package instructions or your preference.
12 tortillas
Assemble the fajitas: Add a generous scoop of the cooked chicken and veggie mixture to each tortilla. Squeeze fresh lime juice over the filling and top with diced avocado, sour cream, shredded mozzarella, and chopped cilantro.
1 handful fresh cilantro, 2 tablespoon sour cream, 1 avocado, 1 cup mozzarella, 1 lime