In a large mixing bowl, whisk together the lime juice, olive oil, chili powder, garlic powder, cumin, salt, and pepper. Add the chicken breasts and coat them thoroughly in the marinade. Let them sit for at least 15 minutes for the flavors to soak in (up to 2 hours for a deeper flavor).

Preheat your grill or grill pan to medium-high heat. Once hot, place the marinated chicken on it. Grill for about 6-7 minutes on each side or until the chicken is fully cooked (juices should run clear and the exterior should be slightly charred). Allow the chicken to rest for a few minutes, then slice.

While the chicken is grilling, combine diced avocado, halved cherry tomatoes, finely chopped red onion, chopped cilantro (if using), and a splash of lime juice in a mixing bowl. Gently toss everything together and season with salt and pepper to taste.

Arrange the sliced grilled chicken on a platter, topping it generously with the fresh avocado salsa. Enjoy your delicious meal warm!