In a mixing bowl combine the vinegar, shallot, garlic, mustard, salt and pepper and whisk to combine. Combine the vegetable oil and olive oil in a measuring cup. While continuously whisking the vinegar mixture, add the oil in a slow, steady stream, until completely emulsified. Whisk in the fresh herbs and set aside as you prepare the salad.
In a large bowl, combine the cantaloupe, red onion, prosciutto, arugula and almonds. Drizzle with 1/2 cup of the vinaigrette and season lightly with salt and pepper. Toss gently to combine; all ingredients should be well coated with the vinaigrette. Serve immediately.