Mix the fajita seasoning in a small bowl with the cornstarch. Add ¼ cup of the oil and the juice of 1 lime and whisk to combine. Thin the mixture with water if it's too pasty. Set aside.

Slice the chicken breast into ¼" thick slices and place in a shallow bowl or zippered freezer bag if making ahead for meal prep. Add ⅔ of the fajita seasoning marinade and toss to coat the chicken well. Set aside.

While the chicken marinades, slice the bell peppers and onion and place in a shallow bowl or zippered freezer bag if making ahead for meal prep. Add the remaining ⅓ of the marinade and toss the vegetables until well coated. Set aside.

Heat 1 tablespoon of the oil in a large cast iron skillet or heavy bottomed pan over medium-high heat and add the vegetables. Cook until the onion softens and the peppers take on color, stirring occasionally, for 4-5 minutes. Transfer to the shallow bowl.

Heat the remaining oil in the skilled and cook the chicken undisturbed until bottom of the chicken pieces begin to turn white, the bottoms are browned, and the chicken releases its juices, about 4 minutes each side. Add the peppers and onion back to the skillet and cook for another 2-3 minutes until everything is warmed through. Remove from the heat and give the dish a squeeze of the remaining lime.

Serve with warm flour tortillas, pico de gallo, avocado sauce, crema, and more lime wedges.