There are many ways to grill corn, but this method keeps the kernels moist and tender. A short immersion in a lightly salted brining solution helps prevent the corn from drying out on the grill. Don't brine the corn longer than the specified time, or it'll be too salty.
Place the water, salt and sugar in a large bowl or pot and whisk until the salt and sugar have dissolved. Add the corn and make sure the ears are completely submerged in the liquid. If necessary, weigh them down with a plate. Let sit at room temperature for 30 minutes.
Remove the corn from the brining solution and dry the ears thoroughly before grilling. Grill over high heat, rotating the ears every few minutes as the kernels char slightly. To serve, brush with melted butter.