Preheat a gas grill or prepare a fire in a gas grill.
Place the corn on the hottest part of the grill and cook for 3 minutes, or until grill marks appear on the first side. Roll each ear over a quarter turn and cook for 2 to 3 minutes, then repeat two more times.
Meanwhile, mix the oil and vinegar on a large flat plate. Spread the Parmigiano on another flat plate.
When the corn is cooked, roll each ear in the oil and vinegar mixture, shake off the extra oil, and dredge in the Parmigiano to coat lightly. Place on a platter, sprinkle with the mint and pepper flakes, and serve immediately.