Halve the cantaloupe and scoop out the seeds and stringy pulp with a spoon.
Cut the melon into wedges about 2 cm thick, then slice the rind away from each wedge with a knife.
Chill the wedges in the fridge for at least 15 minutes, or up to a day, covered, so they're cold when served.
About 10 minutes before serving, take the prosciutto out of the fridge so the fat softens slightly.
Arrange the chilled melon wedges on a 30 cm / 12-inch platter, slightly overlapping.
Drape one slice of prosciutto over or beside each wedge, letting it fall in loose folds rather than pressing it flat.
Drizzle the olive oil over the platter, squeeze the lime juice over everything, and finish with a generous crack of black pepper.
Scatter mint leaves over the top if using, and serve right away while the melon is cold and the prosciutto is at room temperature.