Light a grill. In a small bowl, combine the lime zest with the sugar. Grill the melon wedges over high heat, turning once, until caramelized, about 1 minute. Transfer the melon to a baking sheet and sprinkle with some of the lime sugar. Refrigerate until
chilled.
Sprinkle the melon with more lime sugar and serve with lime wedges, passing any remaining sugar at the table.