Preheat an outdoor grill or grill pan over medium heat.
Remove husk and silk from the corn. Set aside.
In a small bowl, mix mayonnaise, sour cream, and lime juice and stir to combine. Set aside.
In a skillet over medium-high heat, melt butter. Add panko, cumin, chili powder, onion powder, garlic powder, and kosher salt. Stir to toast evenly, about 3-4 minutes.
When the grill is hot, cook the corn until slightly blackened and the kernels are just tender (about 5-7 minutes), turning frequently. Remove the corn from the grill.
Brush the corn with the mayonnaise mixture, then sprinkle with cotija cheese, the toasted panko, and cilantro. Serve warm.