Bring potatoes and water to cover to a boil in a large Dutch oven over medium-high heat; cook 20 to 25 minutes or until tender. Drain and toss with 2 Tbsp. olive oil.
Stir together lemon rind, next 5 ingredients, and remaining 2 Tbsp. olive oil.
Coat a cold cooking grate with cooking spray, and place on grill over medium-high heat (350° to 400°). Place potatoes on cooking grate, and grill, covered with grill lid, 5 minutes, turning occasionally. Gently toss hot potatoes with lemon mixture. Serve immediately or at room temperature.