Preheat your oven to 425°F (220°C).
In a large mixing bowl, combine the sliced chicken, bell peppers, and onion.
Drizzle the olive oil over the mixture and sprinkle the chili powder, cumin, garlic powder, onion powder, salt, and pepper. Toss everything together until the chicken and vegetables are well coated with the spices and oil.
Spread the chicken and vegetables evenly across the sheet pan in a single layer.
Bake in the preheated oven for 25 minutes, or until the chicken is fully cooked and the vegetables are tender and slightly caramelized, stirring halfway through.
While the chicken and vegetables are baking, warm the tortillas in a dry skillet or wrap them in aluminum foil and place them in the oven for the last 5 minutes of cooking.
Remove the sheet pan from the oven and allow it to rest for 5 minutes before serving.
Serve the chicken and vegetable mixture in the warm tortillas, topped with your choice of sour cream, salsa, avocado, lime wedges, and fresh cilantro.