In a shallow bowl mix 1/2 cup grated queso Cotija or Parmesan cheese with 1 teaspoon piquin chile powder. Set aside. Remove the outer leaves and silk from each ear of corn, leaving a single layer of leaves to protect the kernels. In an 8-quart stockpot, bring 3 quarts of water to boil over high heat. Add 2 tablespoons sugar, 2 tablespoons Kosher salt and stir to dissolve, then add 12 ears of corn. When the water returns to a boil, let the corn cook for about 5 minutes, or until tender. Wrap each ear in a sheet of aluminum foil and grill for about 10 minutes turning every 3 minutes, until the kernels, are lightly browned. Pull the leaves down to create a handle for the corn. Rub lime halves over the kernels, then spread mayonnaise evenly over the kernels. Coat the ears with the cheese mixture and serve right away.
