Preheat the oven to 375 degrees F.
Cut the loaf of bread in half crosswise, then cut each half lengthwise into 1-inch thick slices. Lay the slices in a single layer on baking sheets. Generously drizzle
the top side of each slice with olive oil and season with salt and pepper to taste. Sprinkle the Parmesan over the slices. Cook in the oven until golden brown, about 10 to 12 minutes. Set aside.
Marinate the onions
in the vinegar
for 5 minutes. While the onion is marinating, peel
the melon and place in a bowl. Add the diced melon
to the onions, season with salt and stir to blend
together. Add the minced parsley and stir to combine.
Wrap the end of each crostini
with a piece of prosciutto
. Arrange on a platter and spoon a tablespoon of melon salsa on each and serve. Serve remaining salsa
on the side.