Combine the first 7 ingredients in a bowl. Add the pork leg and marinate in the fridge overnight, turning occasionally. Soak the wood chips in cold water for 1 hour. Drain the chips and place in your smoker box, or fold and seal inside an 18-inch x 12-inch piece of tin foil. If using foil, poke the packet created with a fork to allow smoke to escape.
Heat your barbecue to medium-high. Set the wood chips directly on the coals on one side of the barbecue. Remove the pork from the marinade and set, fat-side up, on the grill on the other side of the barbecue. Close the lid and turn the heat off underneath the pork; leave the other side of the barbecue set to medium-high. Barbecue the pork 75 to 80 minutes, or until the temperature in the centre of the roast registers 160 degrees F on an instant-read meat thermometer. While the pork cooks, place the marinade in a pot and simmer until reduced to 1/3 cup.
When the pork is cooked, brush with the reduced marinade and let it heat through a few minutes. Transfer the pork to a plate; rest 10 minutes and then slice.
Note: Wood chips are available in bags at most stores selling barbecuing equipment.