In a small bowl, whisk together the olive oil, lime juice, lime zest, chili powder, brown sugar, salt, cumin, smoked paprika, onion powder, garlic powder, chipotle chili powder, and black pepper.
Coat the chicken breasts evenly with the rub mixture, making sure every side is covered.
Let the chicken rest at room temperature for 30 minutes, or refrigerate for up to 8 hours for deeper flavor. Bring refrigerated chicken to room temperature before cooking.
While the chicken marinates, prepare the avocado salsa. Combine the avocados, tomatoes, corn, red onion, bell pepper, jalapeño, cilantro, garlic, lime juice, cumin, salt, and pepper in a large bowl. Gently toss and refrigerate until ready to serve.
Heat a grill, grill pan, or large skillet over medium-high heat.
Cook the chicken for 5–7 minutes per side, depending on thickness, until the internal temperature reaches 165°F (74°C).
Transfer the cooked chicken to a plate and let it rest for 5 minutes.
Top each chicken breast generously with avocado salsa and serve immediately. This Fiesta Lime Chicken Recipe is best enjoyed fresh.