Rinse and drain the tarragon, then finely chop. Slice the lemon in half and grill one half over high heat, cut-side down. Press the juice of the grilled lemon half and combine with the mayonnaise and tarragon. Season with salt and pepper.
Carefully wash the potatoes. Cut lengthwise into thick sticks and coat with oil, salt and pepper. Place them in the fine-mesh rotisserie basket. Attach the basket to the rotisserie spike.
At the barbecue:
Prepare the grill for indirect high heat. Place the rotisserie with the fine-mesh basket on the grill and start the motor. Grill the potatoes for 1 hour – or until crispy. Sprinkle the cooked potatoes with coarsely chopped rosemary.
Prepare the grill for high heat. Place the rotisserie with the fine-mesh basket on the grill and start the motor. Grill the potatoes for 1 hour – or until crispy. Sprinkle the cooked potatoes with coarsely chopped rosemary.
