I add the tequila and lime juice to the chicken marinade to add a brightness and “kick” that contrasts with the smokiness of the chicken cooked on the grill.
In a large mixing bowl whisk together the tequila, vegetable oil, lime juice, chili powder, cayenne powder, garlic and salt until combined. Add the strips of chicken to the marinade then cover and refrigerate for at least 1 hour and up to 4 hours.
For the fajitas:
Heat a large cast-iron skillet over medium heat, add the olive oil and heat through. Add the onions and sauté for 3 minutes.
Add the bell peppers and continue to sauté, stirring occasionally, until the some char marks appear and the onions and peppers are tender, about 4 to 5 minutes.
Remove the onions and peppers to a medium mixing bowl and return the pan to medium heat.
Add the remaining olive oil and heat through. Add the chicken and cook, stirring occasionally, until the chicken is cooked through, about 8 minutes.
Add the onions and peppers back to the pan, stirring to combine.
Serve the mixture alongside warmed tortillas, sour cream and lime wedges.