Carefully peel back the corn husks until they’re about 1 inch away from the bottoms. Remove the silk using a produce brush under running water or by rubbing the cob with a gloved hand.
Rewrap each ear of corn in its husk and secure them with kitchen string.
Place the ears of corn in a Dutch oven, and cover them with cold water. Let them soak for 20 minutes and then drain them.
While you’re waiting for the corn to soak, preheat your grill to medium heat. Grill the corn in their husks, covered, over medium heat until the corn is tender, about 25 to 30 minutes. Turn the ears of corn often.
Combine the sour cream, mayonnaise, cilantro, garlic, lime zest and lime juice in a medium bowl. Peel back the husk on each ear of corn and spread the mixture generously over the kernels.
Sprinkle each ear of corn with Cotija cheese and chili powder and serve them on a platter, or let everyone assemble an ear of corn so the toppings are to their liking.
