01 - In a large bowl, whisk together lime juice, lime zest, olive oil, garlic, chili powder, cumin, paprika, salt, and pepper. Add chicken breasts and turn to coat evenly. Cover and marinate for at least 20 minutes, or up to 2 hours refrigerated.
02 - Preheat grill or skillet to medium-high heat. Remove chicken from marinade and grill 6 to 7 minutes per side until cooked through and internal temperature reaches 165°F.
03 - While the chicken cooks, combine diced avocados, tomato, red onion, cilantro, lime juice, and salt in a bowl. Gently toss to combine.
04 - Transfer cooked chicken to plates. If desired, sprinkle shredded cheese over each breast while hot so it melts slightly.
05 - Top each chicken breast with a generous spoonful of avocado mixture. Finish with lime wedges and extra cilantro. Serve immediately.