Fire up your grill for direct grilling.
Tear off a large piece of aluminum foil.
Add radishes to the center of the foil. Sprinkle with the garlic, butter, and salt and pepper.
Top the radishes with the ice cube.
Fold the edges of the foil over and pinch to seal.
Place on the grill for 20 minutes or until tender.
Serve immediately with more salt and pepper.