Pour the margarita mix over the chicken breasts and marinate for 2 hours in the refrigerator.
When ready to prepare, drain and season the chicken with salt and black pepper. Discard the marinade.
Heat a grill to 450°F (medium-high).
Grill the chicken until the internal temperature reaches 165°F. Turn the chicken halfway through grilling.
If you do not have a grill, heat a cast iron skillet over medium-high heat. When it reaches temperature, spray the skillet with oil. Cook the chicken breast on each side until the internal temperature reaches 165°F, about 5 to 7 minutes on each side.
To serve margarita grilled chicken like Chili's, place the grilled chicken breast on top of black beans, Mexican rice, and tortilla strips, and top with pico de gallo.
Do not marinate the chicken for more than 2 hours, the protein will begin to break down.
Discard all extra marinade, it can not be used again.
If the chicken breasts are very large, consider slicing horizontally to cut down the portion size.