Preheat gas grill; set the burners to high, cover, heat grill 10 minutes. Scrape and clean grates if necessary.
For a charcoal grill: Light 5-6 quarts of charcoal briquettes in a chimney starter. When briquettes are partially covered with ash, 15-20 minutes, pour into grill making an even layer. Place grates on the grill, clean, if necessary, heat for 5 minutes.
While the grill heats prepare the cream coating. In a bowl combine the mayonnaise, sour cream, ¾ cup of the Cotija, lime juice, garlic, ¾ teaspoon chili powder, cayenne pepper, black pepper, and 1 tablespoon cilantro. Mix until well combined, cover and refrigerate until ready to use. Reserve the remaining ¼ cup of cheese and tablespoon of cilantro for garnish.
Brush corn with vegetable oil, season with the remaining ¼ teaspoon of chili powder, and salt.
Grill corn, covered, until lightly charred on all sides, 15 minutes, turning 3-4 times for even cooking.
Brush hot corn with the cream mixture, garnish with the remaining Cotija and cilantro, serve warm.
Notes
Don’t skip the oil: It helps with charring and keeps seasonings in place.
Fresh corn is best: Look for ears with full corn kernels and no soft spots.
Make it your own: Use feta cheese or queso fresco if cotija isn’t available, or swap sour cream for Mexican crema.
To Store: Remove kernels from the cob and store in an airtight container in the fridge for up to 3 days.
Freezing is not recommended: The creamy coating won’t hold up well.
To Enjoy Later: Eat it cold as a corn salad, just don’t try to reheat with the cream coating because it may curdle.