Place the first 8 ingredients in a blender; cover and process until smooth. Place arugula, onion and herbs in a large bowl. Drizzle with 1/3 cup vinaigrette and toss lightly to coat. In large serving bowl layer with a quarter of the arugula mixture, honeydew, mozzarella cheese and prosciutto. Repeat layers 3 times. Serve with remaining vinaigrette.