For gas grill: Preheat BBQ to medium heat. Once preheated, turn off half of the burners for an indirect/direct heat source. This is so that you can use the indirect heat side to keep the finished cobs warm until serving.For charcoal grill: Light 1 chimney full of charcoal. When all charcoal is lit and covered with gray ash, pour out and arrange coals on one side of the grill. Set cooking grate in place, cover the grill, and preheat for 5 minutes.
Clean and oil the grilling grate. Mix the butter with the Mexican seasoning. Place the cobs on the grill and brush them with the Mexican seasoning butter.
Grill the cobs until they are tender and you start seeing the black grill line. This should be about 10 minutes per side. Half way through, turn them over and brush them with more butter.
The cobs can be kept warm on the indirect heat side of the BBQ. When ready to eat, remove corn from grill. Add more butter, sprinkle with salt, and serve.