Directions
Preheat an outdoor grill for medium-high heat and lightly oil the grate.
Mix black beans, salsa, 1/2 cup cilantro, and lime juice in a bowl; set aside.
Stir chili powder, cumin, coriander, brown sugar, cayenne pepper, and olive oil in a bowl until smooth; rub mixture over chicken breasts.
Cook chicken breasts on preheated grill until no longer pink in the center and the juices run clear, 10 to 12 minutes per side. An instant-read thermometer inserted into the center should read at least 165 degrees F (74 degrees C). While the chicken is cooking, place tortillas on grill and grill until lightly brown on both sides, 3 to 5 minutes.
Transfer chicken to a cutting board and slice into long thin strips. Divide chicken strips over tortillas and top with bean mixture, lettuce, and remaining 1/2 cup cilantro. Serve with avocado, lime wedges, and sour cream.