Preheat grill to 450 degrees.
Place potatoes and water in microwaveable bowl. Cover and cook for 5 minutes until potatoes are just fork tender but not falling apart. Drain.
Stir together butter, oil, herbs and salt and pepper to taste. Toss potatoes with herbed butter mixture.
Place two pieces of heavy-duty foil on top of each other. Pour potato mixture onto foil. Fold and seal edges to form a packet. Grill for 30-35 minutes, turning every 8 minutes. Serve warm.