Preheat oven to 375°F.
Coat the chicken breasts with 1/2 cup of the pesto and reserve the remaining 1/4 cup in the refrigerator. Place the pesto-rubbed chicken on a baking sheet and bake for 25 minutes, or until an instant read thermometer reads 165°F. Allow the chicken to cool slightly before slicing into half-inch pieces and tossing with the reserved pesto.
For each taco, layer chicken with 1 slice avocado, 1 slice fresh mozzarella, 1 half-moon slice of tomato, 1/2 tbsp. basil, and 1/4 tsp. balsamic glaze.