Here are 2 natural ways to cook corn, without aluminum foil. Both recommend pre-soaking the corn and keeping the husks on while grilling.
Preliminaries. About an hour before serving, place the ears of corn in a deep bowl, cover with cold water and weight with a plate to keep them submerged. Light your charcoal fire and let it burn until the bed of coals is medium-hot; adjust the grill 4 inches above the fire.
Grill the corn. Lay the corn on the grill and roast for 15 to 20 minutes, turning frequently, until the outer leaves are blackened. Remove, let cool several minutes, then remove the husks and silk. About 10 minutes before serving, brush the corn with melted butter, return to the grill and turn frequently until nicely browned.
Techniques. Soaking in Water, Roasting in the Husk: The preliminary soaking keeps the outside from burning right off the bat and the inside damp enough to steam. First roasting in the husk penetrates the corn with leafy flavor, but the step is often omitted—especially with sweet corn.