Combine the marinade ingredients in a blender or food processor and process for 1 minute to purée. Set aside 250 ml of the marinade to use as a basting sauce.
Remove the thin membrane from the back of each rack of ribs. Season the ribs on the meaty sides with salt. Brush the remaining marinade over all the ribs, allow to stand at room temperature for 30 mins before cooking. Prepare the barbecue for the roasting (indirect) method over a low heat.
Brush the cooking grates clean. Stack the ribs on top of each other, with the bone sides facing down, and roast using low heat for 45 minutes, with the lid closed.
Undo the stack of ribs on the barbecue again. Brush the meaty sides with some of the reserved marinade. Stack the ribs, with the bone sides facing down, moving the top rack to the bottom, the bottom rack to the center, and the middle rack to the top. Barbecue for another 45 minutes, with the lid closed.
Undo the stacks of ribs on the barbecue again. Brush the meaty sides with some of the reserved marinade. Stack the ribs, with the bone sides facing down, moving the top rack to the bottom, the bottom rack to the center, and the middle rack to the top. Continue cooking for 1-1½ hours, with the lid closed. During this third round of cooking, move the relative positions of the ribs occasionally so that the racks that are browning a little fast cook in the center of the stack and the racks that are not as brown cook at the top of the stack. As you move the ribs, brush the meaty side’s with the reserved marinade.
Undo the stack of ribs and place them side by side, with the bone side facing down, over direct low heat for 10 to 15 minutes, turning occasionally to prevent burning. Brush with a little more of the reserved marinade and continue cooking until the meat is very tender and has shrunk back from the ends of the bones.
Undo the stack of ribs and place them side by side, with the bone side facing down, over low heat for 10 to 15 minutes, turning occasionally to prevent burning. Brush with a little more of the reserved marinade and continue cooking until the meat is very tender and has shrunk back from the ends of the bones.
Transfer the racks to a roasting tray, cover with foil and allow to rest for 15 minutes before cutting into individual ribs. Serve warm.
