Prepare the Kettle for indirect cooking over high heat (230°C to 260°C).
Mix together all the rub ingredients in a small bowl. Trim off most of the fat from the rack of lamb. Lightly coat both sides of the lamb racks with oil and season with the spice rub. If desired, wrap the exposed bones with aluminium foil to protect the bones from burning.
Roast the lamb over indirect high heat, with the lid closed, for 25 to 35 minutes, or until cooked to your liking.
While the lamb is cooking, prepare the Chimichurri board dressing. On your chosen wooden serving board, finely chop the garlic. Add the parsley and coriander leaves to the garlic and finely chop. Add the remaining ingredients to the board, keeping the ingredients in the centre of the board. Using a fork, blend together the ingredients.
Once the lamb has cooked to your liking, sit the racks on the wooden serving board, meaty side down, on top of the dressing. Leave to rest for a couple of minutes before carving. Encourage your guests to drag both sides of the lamb cutlets through the dressing.