Split and toast the hoagie rolls in 350 degree oven until slightly crisp.
To prepare: Layer hoagie rolls with arugula, prosciutto, and freshly sliced mozzarella cheese. Top with desired condiments such as Dijon mustard or balsamic glaze.
Serve. (Tip: This makes a great meal to pack for a picnic! Just make sure to bring along any utensils necessary for assembling.)