Marinate the chicken by whisking together lime juice, olive oil, cumin, garlic powder, onion powder, salt, and black pepper. Coat the chicken and refrigerate for at least 30 minutes.
Preheat the grill to medium-high heat. Grill the chicken for 6-7 minutes on each side until the internal temperature reaches 165°F. Let it rest for 5 minutes.
Prepare the avocado salsa by combining diced avocados, tomato, red onion, jalapeño, lime juice, salt, and pepper in a bowl. Toss gently.
Slice the grilled chicken and serve topped with avocado salsa and additional cilantro if desired.