Lay out 2 large pieces of aluminum foil, each about 12 x 15 inches. Place potatoes and several springs of thyme in center of 1 sheet of foil; drizzle with water and 2 tablespoons of the Zesty Ranch and sprinkle with salt and pepper to taste. Fold foil over potatoes, folding along all 4 edges. Grill potato packet until tender, about 20 minutes.
Place plums, shallots and several more thyme springs in the center of other foil sheet. Drizzle with remaining 1 tablespoon Zesty Ranch and sprinkle with salt and pepper to taste. Fold foil over plum mixture, folding along all 4 edges. Grill plum packet until tender, about 12 minutes.
Meanwhile, rub pork with Slow Roasted Garlic and season to taste with salt and pepper. Grill, turning every 2 minutes until internal temperature reaches 145 degrees, about 16 minutes total. Brush with Honey Mustard in the last few minutes of cook time.