01 - Preheat grill or grill pan to medium-high heat. Season chicken breasts with a pinch each of salt, pepper, and chili powder. Grill for 6-7 minutes per side until cooked through and juices run clear. Remove and let rest for 5 minutes, then dice into bite-sized pieces.
02 - Place corn cobs on the grill, turning occasionally, until lightly charred for 8-10 minutes. Let cool, then slice kernels off the cob. If using frozen corn, sauté in a dry skillet over high heat until lightly charred.
03 - In a large bowl, whisk together mayonnaise, sour cream, lime juice, chili powder, smoked paprika, garlic powder, salt, and black pepper until smooth and well combined.
04 - Add diced chicken, charred corn, cucumber, cherry tomatoes, red onion, and cilantro to the bowl with dressing. Toss gently to coat all ingredients evenly.
05 - Sprinkle with cotija cheese and extra cilantro. Serve immediately or refrigerate for 30 minutes to allow flavors to meld. Garnish with lime wedges if desired.