In a large bowl, whisk together olive oil, lime juice, honey, chili powder, cumin, garlic powder, onion powder, salt, black pepper, and cayenne pepper (if using). Add the chicken breasts and coat them well in the marinade. Cover and refrigerate for at least 30 minutes, or up to 4 hours for more flavor.

Preheat the grill to medium-high heat. Remove the chicken from the marinade and discard the marinade. Grill the chicken for 6-7 minutes on each side, or until the internal temperature reaches 165°F.

While the chicken is grilling, prepare the avocado salsa. In a medium bowl, combine diced avocados, cherry tomatoes, red onion, cilantro, lime juice, salt, and pepper. Gently toss to combine.

Once the chicken is cooked, remove it from the grill and let it rest for 5 minutes. Slice the chicken and serve it topped with avocado salsa.