Grill or boil the corn until tender, then cool and cut the kernels off the cob.
In a large mixing bowl, combine the corn kernels, diced tomatoes, and chopped red onion.
Add the chopped cilantro and crumbled cotija cheese to the bowl.
In a separate bowl, mix the mayonnaise, lime juice, chili powder, salt, and pepper.
Pour the dressing over the corn mixture and gently toss to combine.
Taste and adjust seasoning if necessary.
Serve immediately or refrigerate for at least 30 minutes to let flavors meld.
Garnish with additional cilantro and lime wedges before serving.