Preheat the oven to 400°F.

Line an extra-large baking sheet with parchment paper.

In a medium bowl, whisk together the olive oil, chili powder, cumin, coriander, garlic powder and dried oregano.

Remove the seeds from the bell peppers and slice into strips 1/2 inch thick. Slice the onion into 1/4 inch-thick crescents. Transfer the peppers and onion to a large mixing bowl.

Drizzle 2 tablespoons of the spiced oil over the vegetables. Sprinkle with the salt and black pepper and toss to coat.

Arrange the peppers and onions in a single layer on the prepared baking sheet. Roast the vegetables on middle rack of oven for 10 minutes. While the vegetables roast, prepare the chicken.

Cut the chicken into strips roughly 3/4 inch wide. Transfer to the large mixing bowl used for the vegetables.

Season the chicken with the salt and black pepper. Drizzle the remaining spiced oil over the chicken and toss until it is evenly coated.

Carefully remove the baking sheet from the oven. Arrange the sliced chicken on the baking sheet. The chicken may cover some of the vegetables.

Return the baking sheet to the oven and continue baking until the chicken is cooked through and the vegetables are tender and slightly charred, 17-20 minutes.

Check to see that fajitas are done. Remove from oven or add time as needed.

Squeeze the juice from half a lime over the chicken. Sprinkle with chopped cilantro. Serve fajitas with corn tortillas, salsa, sour cream, avocado, and shredded cheese, if desired.