Preheat a grill or skillet over medium-high heat
Husk the corn and remove the silk
Brush the corn with a little oil or butter
Cook the corn, turning often, until lightly charred and tender
Mix mayonnaise with sour cream or Mexican crema
Stir in lime juice and a pinch of salt
Spread the mayo mixture over the hot corn
Sprinkle generously with crumbled cotija cheese
Dust with chili powder or TajÃn
Add chopped cilantro if desired
Serve with lime wedges on the side