In a bowl, combine olive oil, lime juice, chili powder, cumin, smoked paprika, onion powder, garlic powder, brown sugar, and salt to create a marinade. Rub this mixture generously over the pounded chicken breasts, ensuring they're evenly coated. Cover and let the chicken marinate in the refrigerator for at least 30 minutes or up to 8 hours for more intense flavor.

When ready to cook, preheat a skillet over medium-high heat or prepare your grill to medium temperature. If skillet cooking, add a splash of olive oil and place the marinated chicken in the pan. Sear for 3-5 minutes until browned, then flip, cover, and cook for another 5-7 minutes until the internal temperature reaches 165°F. If grilling, cook the chicken undisturbed for 5-7 minutes per side until done.

Once cooked, transfer the chicken to a plate and let it rest for 5 minutes. During this time, prepare the avocado corn salsa.

In a large mixing bowl, combine diced avocados, halved cherry tomatoes, corn, finely chopped red onion, minced jalapeño, fresh cilantro, minced garlic, and a squeeze of additional lime juice. Gently toss to mix, being careful not to mash the avocados.

Slice the rested Fiesta Lime Chicken and arrange it on a serving platter. Top generously with the vibrant avocado corn salsa.