In a bowl, combine all Marinade ingredients. Add Chicken and marinate for at least 1 hour, or up to 8 hours in the refrigerator.
Heat 2 tbsp Olive oil in a large cast-iron skillet over medium-high heat. Add Red onion and Bell peppers and sauté for 8-10 minutes, until softened and slightly charred.
Remove vegetables from the skillet and set aside. Add marinated Chicken to the skillet and cook for 7-9 minutes, or until cooked through.
Return vegetables to the skillet and toss with Chicken. Warm tortillas in a dry skillet or microwave.
Serve Chicken and vegetable mixture in warm tortillas with desired toppings.
