Combine first 5 ingredients, tossing gently. Arrange melon mixture on a serving platter. Arrange prosciutto evenly over melon mixture; sprinkle with Parmigiano-Reggiano. Garnish with cracked black pepper and fresh mint sprigs, if desired.
Wine note: I adore the sweet-salty-herbal flavor of this salad. It's so refreshing and so summery. A good wine partner should exude the same characteristics. While you could opt for an Italian pinot grigio, I find a fuller-bodied California pinot grigio works even better, especially given the full flavors of the prosciutto, mint, and Parmigiano. A great choice: Estancia Pinot Grigio 2005 (California), $12. --Karen MacNeil