1. Turn all grill burners to high and heat grill with lid down until very hot, about 15 minutes. Scrape grate clean with grill brush. Dip wad of paper towels in vegetable oil; holding wad with tongs, wipe cooking grate.

2. While grill is heating, combine mayonnaise, sour cream, cilantro, garlic, 1/4 teaspoon chili powder, black pepper, cayenne (if using), lime juice, and cheese in large bowl; set aside. In second large bowl, combine oil, salt, and remaining 1/2 teaspoon chili powder; add corn and toss until coated evenly.

3. Leave burners on high and cook corn with lid down, turning corn occasionally, until lightly charred on all sides, 7 to 12 minutes total. Remove from grill and place in bowl with mayonnaise mixture; toss to coat evenly. Serve immediately.

Serves 6