Preheat your grill to medium-high heat.
Season the chicken breasts with salt and pepper.
Grill the chicken for about 6-7 minutes on each side, or until fully cooked.
Remove the chicken from the grill and let it rest for 5 minutes before slicing.
In a large bowl, combine diced avocado, halved cherry tomatoes, and mozzarella balls.
Slice the grilled chicken into strips and add to the bowl with other ingredients.
Drizzle the balsamic reduction over the ingredients and toss gently to combine.
Garnish with fresh basil leaves before serving.
