Blanch the potatoes for 10 minutes. Once cool enough to handle, cut the new potatoes into 1cm thick slices and toss in olive oil, seasoning with freshly ground black pepper.
Lay the potatoes on a double layer sheet of foil and tuck in the bruised garlic cloves and sprigs of thyme. Seal the foil up tightly to make a neat parcel and barbecue for 30-40 minutes, turning the parcel over occasionally.
Make the dressing by mixing together the sundried tomatoes, mayonnaise and chives. Season with freshly ground black pepper.
When the barbecue roasties are ready, tip into a bowl and top with the dressing.