Preheat your oven to 400°F (200°C). Make sure the rack sits in the middle.
Combine sliced chicken, bell peppers, and onion in a large bowl.
Drizzle with olive oil and sprinkle with chili powder, cumin, paprika, salt, and pepper. Toss to coat evenly.
Spread the mixture in a single layer on a sheet pan.
Bake in the preheated oven for about 20-25 minutes or until the chicken is cooked through and vegetables are tender.
Serve in tortillas and enjoy.
Notes
Ensure to preheat the oven to avoid uneven cooking. You can use zucchini or mushrooms if you don't have bell peppers, and chicken thighs work well as a substitute.