1. Divide arugula into 8 small bunches and loosely wrap each with 1 or 2 slices prosciutto. Divide among 4 plates with roasted peppers, olives, and onion.
2. Whisk together vinegar, anchovy, and 1/4 teaspoon each of salt and pepper. Whisk in extra-virgin oil.
3. Whisk egg whites with 1/2 teaspoon salt and 1/4 teaspoon pepper in a shallow bowl. Put bread crumbs in another shallow bowl. Double-coat each slice of cheese by dipping in egg mixture, then crumbs, and repeating. Transfer to a plate.
4. Heat 1/2 inch olive oil in a 12-inch heavy skillet over medium-high heat until it shimmers. Fry coated mozzarella, turning carefully once or twice, until golden and cheese starts to melt but still retains its shape, about 2 minutes total. Drain briefly on paper towels, then transfer to plates.
5. Drizzle everything with vinaigrette.
6. Serve with: garlic bread with parsley