In a medium bowl, gently fold together corn, avocado, red onion, lime juice, jalapeno if using, remaining 1/4 tsp salt, and 2 tbsp chopped cilantro. Taste and adjust lime or salt. Set aside - the lime juice will keep the avocado green while you cook the burgers.

In a large bowl, use your hands to gently combine ground chicken, garlic, 1/4 cup cilantro, cumin, 1/2 tsp salt, and pepper. Do not overmix or burgers will be tough. Divide into 4 equal portions and shape into 3/4-inch thick patties, making a slight depression in the center of each to prevent puffing.

Heat olive oil in a grill pan or outdoor grill over medium-high heat until shimmering. Add patties and cook without moving for 5-6 minutes until well-browned and release easily. Flip and cook 4-5 minutes more until internal temperature reaches 165°F. The center should feel firm when pressed.

While burgers rest, toast the brioche buns cut-side down on the grill pan or grill for 1-2 minutes until golden and slightly crisp.

Place each chicken patty on a toasted bun bottom. Spoon a generous 1/3 cup of avocado corn salsa over the patty, letting some spill onto the plate. Top with bun and serve immediately with extra salsa on the side.