Put the ribs in a large saucepan of salted water with the lemon slices. Bring to a boil, reduce the heat to low, and simmer gently for 40 minutes to tenderize the meat.
Meanwhile, put the remaining ingredients in a blender or food processor, and blend well to make a smooth sauce. When the ribs are cooked, remove from the pan with a slotted spoon, and drain thoroughly in a colander. Place the ribs in a bowl, coat with the sauce, and leave to cool. Marinate in the refrigerator for at least 1 hour.
Heat the barbecue until hot. Place the whole rib racks on the barbecue, and grill over a medium heat for 30 minutes, turning frequently and basting with any leftover sauce.
Transfer to a plate, and allow to rest in a warm place for 5 minutes. To serve, slice the racks into ribs, and serve warm and sticky with a crunchy salad and plenty of napkins.