Step 1

In a mixing bowl, toss the potatoes with 1/3 of the olive oil. Season well with salt and pepper.

Step 2

Lay out a double sheet of foil in a cross and place the potatoes on to it. Gather up the sides to create a foil packet and add 1/4 cup water before sealing.

Step 3

Place directly on to the heated part of the grill and steam for 30 minutes, or until cooked through.

Step 4

While the potatoes are steaming, whisk together the vinegar, mustard, remaining oil, celery seeds, sugar and herbs. Season with salt and pepper. Set aside.

Step 5

Open up the foil and allow the potatoes to take on some smoke and dry out, about 5 minutes.

Step 6

Remove the potatoes from the grill and toss with the vinaigrette. Serve.