In a large bowl, combine the sliced chicken, 2 tablespoons olive oil, minced garlic, chili powder, ground cumin, smoked paprika, dried oregano, salt, black pepper, cayenne pepper, and fresh lime juice. Mix well to coat the chicken evenly.
Cover the bowl with plastic wrap and refrigerate the marinated chicken for at least 2 hours or overnight for best flavor.
About 30 minutes before cooking, remove the chicken from the refrigerator to bring it to room temperature.
Heat 1 tablespoon olive oil in a large skillet or cast iron pan over medium-high heat.
Add the sliced onions and bell peppers to the skillet and sauté for 5-7 minutes until they are tender and slightly charred. Remove the vegetables from the skillet and set aside.
In the same skillet, add the marinated chicken in a single layer. Cook for 6-8 minutes, stirring occasionally, until the chicken is cooked through and slightly browned.
Return the cooked peppers and onions to the skillet with the chicken. Stir to combine and heat through for 2 minutes.
Warm the flour tortillas in a dry skillet or microwave wrapped in a damp paper towel until soft and pliable.
To serve, spoon the chicken and vegetable mixture onto each tortilla. Top with chopped cilantro, shredded cheddar cheese, sour cream, and salsa as desired.