Prepare the bell peppers by cutting off the tops and removing the seeds and membranes inside. Place them upright in a baking dish.
In a large skillet, pour in the olive oil and heat over medium heat. Add the diced chicken and cook for approximately 5-7 minutes until browned and cooked through.
Add the sliced onion, diced zucchini, and the contrasting bell pepper to the skillet. Sauté for an additional 5 minutes until the vegetables are tender.
Sprinkle in the taco seasoning, cumin, and a generous pinch of salt and pepper. Stir together and cook for another 2-3 minutes.
If using rice, fold it into the chicken and vegetable mixture.
Spoon the chicken and vegetable mixture into each prepared bell pepper, packing it tightly. Top each pepper with shredded cheese.
Cover the baking dish tightly with aluminum foil and bake for 25 minutes. Remove the foil and bake for an additional 10 minutes until the cheese is melted and golden.
Allow to cool for a few minutes before serving. Garnish with fresh cilantro.
Serve warm with lime wedges.
Notes
Feel free to adjust the spice level by modifying the taco seasoning.