Mix the lime juice, tequila, pepper flakes, chili powder, and garlic in a glass container and add chicken.
Cover, and marinate in the refrigerator for at least 45 minutes.
Discard marinade and grill chicken until internal temp reaches 165°F. Let chicken rest for several minutes before slicing.
While the chicken is resting, heat oil in a large saute pan over medium heat. Add bell peppers and onion and saute several minutes until soft.
Layer sliced chicken, sauteed vegetables, and extras of your choice in lettuce leaves or tortillas. I love a squeeze of fresh lime on top plus avocado/guacamole, sour cream, and salsa.