Mix all the dressing ingredients except the salt and pepper together in a shaker or clean jam jar and shake together until well blended.
Taste the dressing for seasoning and add salt and pepper if desired. Shake again.
Slice the cherry tomatoes in half.
Peel and slice the peaches or slice the nectarines.
Place the salad leaves and tomatoes in a bowl and toss with most of the dressing. Reserve a little bit of dressing for garnish.
Divide the salad between two plates.
Put three slices of proscuitto on each serving.
Place half the peach slices on top of each salad.
Drizzle with the remaining dressing.
Garnish with the Parmigiano Reggiano shavings.