Pour the vinegar into a small pot and bring it to a boil over high heat. Turn the heat to medium low and reduce the vinegar by about 1/4, or until it is thick. Let cool.
Put a pot of salted water over high heat. Trim the asparagus spears to that they are all the same length. Peel the bottom half of the spears with a vegetable peeler. Tie the asparagus together into a bundle using kitchen string. When the water is boiling, lower the asparagus into the pot and cook until just tender, about 3 minutes. Plunge the asparagus into a bowl of ice water to stop the cooking. When it is completely cold, remove the spears and lay them out onto a rack to dry.
Roll a slice of prosciutto around each asparagus spear. Arrange them on a platter and drizzle over some olive oil. Sprinkle with some pepper and salt. Finally, dribble on some of the reduced balsamic vinegar. Serve immediately.
