Smoky flavors from the grill enrich this potato salad. Serve at room temperature to enjoy the most flavor and best texture it has to offer. You can combine all the ingredients except the arugula up to an hour ahead; just before serving, stir in the delicate greens.
Place potatoes in a medium saucepan; cover with water. Bring to a boil. Reduce heat; simmer 10 minutes or until the potatoes are almost tender. Drain and rinse under cold water; drain well. Place the potatoes in a bowl. Drizzle with 2 tablespoons of Honeyed Lemon-Dijon Vinaigrette; toss gently to coat.
Place potatoes, cut sides down, on grill rack coated with cooking spray; grill 3 minutes on each side or until potatoes are very tender.
Combine potatoes, arugula, and remaining ingredients in a large bowl. Drizzle with remaining 6 tablespoons Honeyed Lemon-Dijon Vinaigrette, and toss gently to coat.