Peel away and trim any tatty outer layers or withered tops from the spring onions. Discard. Put the onions in a large bowl. Dribble over a couple of tablespoons of sunflower oil and lovingly grease the onions.
When the hot, grey-orange coals are pulsing out a fierce heat from the barbecue, lay the onions on the grill rack. Watch them, as they will cook quickly. Turn when deeply browned