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 place them in a large mixing bowl.
3. Add the cotija cheese, cherry tomatoes, red onion, cilantro, and jalapeño to the bowl.
4. In a small bowl, whisk together the lime juice, mayonnaise, chili powder, and salt. Pour over the corn mixture and toss to combine.
5. Serve immediately or refrigerate until ready to serve.