1. Heat a skillet over medium-high heat. Add the corn and cook, turning occasionally, until charred in spots, about 8-10 minutes. Remove from heat and let cool.
2. Cut the kernels off the cob and transfer to a large bowl.
3. Add the cotija cheese, mayonnaise, cilantro, chili powder, lime juice, salt, and black pepper to the bowl. Mix until well combined.
4. Serve immediately or refrigerate until ready to serve.