Boil the potatoes in a large pan of salted water
for about 10 mins until just cooked. In a large
bowl, stir the oil and vinegar together with some
salt and pepper. While the barbecue is still hot,
grill the onion slices for 5 mins on each side until
lightly charred. Toss the hot onions, separating
them into rings, in the dressing.
Toss the potatoes in a small drizzle of oil and
grill on the barbecue, cut side down, for about
5 mins until browned, then toss with the onions.
Mix in the parsley and serve.