Preheat oven to 425 degrees F. Lightly oil a baking sheet or coat with nonstick spray.

In a small bowl, combine chili powder, cumin, oregano, paprika, 1 1/4 teaspoons salt and 1 1/4 teaspoons pepper.

Place chicken, bell peppers, onion and garlic in a single layer onto the prepared baking sheet. Shake seasoning mixture over baking sheet and drizzle olive oil as well to coat evenly.

Place into oven and bake for 25 minutes, or until the chicken is completely cooked through and the vegetables are crisp-tender.

Serve immediately with tortillas.