Pull all of the husks back from the corn without removing it. Pull off and remove all the silk, using a soft brush to get the last stubborn strands. Return the husks to their original position and twist the tops.
In a large deep bowl, cover the corn with cold water and weight down with a plate to keep them all submerged. Let the corn soak for 1 hour. Meanwhile, light a charcoal fire and let it burn until the coals are medium hot. Set the grill rack 4 inches from the hot coals. Lay the corn on the grill rack and roast for 15 to 20 minutes, turning frequently with tongs. Pull back some husks to test the kernels for doneness if desired. Remove from the grill, let cool for a few minutes and pull the husks back to the base again so that you can use them as a handle for picking up the corn. Set aside until ready to serve the rest of the meal. Brush the corn with the butter and return it to the grill rack for about 10 minutes, turning frequently, until nicely browned. Sprinkle the corn with the chile powder and pass the sour cream and cheese at the table for guests to help themselves.
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