Smoking on a charcoal barbecue is quite easy to do, especially if you are already comfortable with barbecuing over indirect heat. Begin by filling a chimney starter about one-third full with briquettes. When the briquettes are fully lit, pour all of the charcoal onto one side of the grate (if desired, use a charcoal basket, which holds the coals close together so that they burn more slowly) and place a large disposable foil tray on the other side. Then, carefully add about 475 to 700 ml of water to the tray. The water in the tray is important because it helps to maintain a low cooking temperature. It also adds some moisture to the food, which in many cases will cook for hours and hours, so it could otherwise dry out. Allow 30 minutes to 1 hour for the coals to burn down to the correct temperature and for the water to heat up. Next, drop damp wood chips or dry wood chunks directly onto the coals. Then place your food on top of the cooking grill over the tray of water and cover your barbecue. Expect to add more coals every hour or so to maintain the heat.