Heat grill to medium high, lightly oiling the grill grate. Place peach slices on the grill. Cook for about 1 minute or until the slices have grill marks. Turn wedges over and cook the other side. Remove from grill. In large bowl, add arugula and set aside.

In a small jar, add vinegar, olive oil, honey, mustard, onion and tarragon. Shake vigorously. Season with salt and pepper and shake again. Add dressing to arugula and toss to coat.

Divide the arugula on four plates topping each with peach slices and prosciutto. Garnish with feta cheese and serve.