2) Trim a slice from the top of each onion and peel the onion without cutting off the root end. With a potato peeler, cut a small cone-shaped section from the centre of the onion. Cut the onions into quarters from the top down, stopping within 2.5cm of the root end.
3) Place a stock cube in the centre of each onion, slip slivers of butter in between the sections and sprinkle with pepper. Wrap each onion in a double thickness of heavy-duty foil.
4) Place the onions directly onto the hot coals and cook for 45 minutes, turning every so often. These can also be baked in a preheated 180C oven for 45 minutes, but I still say they're better cooked over charcoal. Serve in individual bowls because the onions produce a lot of stock, which tastes like French onion soup.