Cut 3 thin slices off the melon for decorating, wrap them in cling film and refrigerate. De-seed peel, cube and purée the rest of the melon. Push the purée through a fine sieve.
Beat your egg whites until they form stiff peaks, while slowly adding the maple syrup. Mix the beaten egg whites into the melon purée. Either cool the mixture in an ice cream maker for 40 minutes, or place it in a metal bowl and freeze it for at least 2 hours to harden, stirring it occasionally so the sorbet gets creamy
Before serving, crush the peppercorns and wash the mint leaves.
Let the finished sorbet stand for a minute, then fill it into a piping bag with a star tip and squeeze into chilled glasses. Serve with melon slices and peppercorns or mint leaves as a garnish.