Score the skin with the tip of a sharp knife in a lattice fashion, being careful not to pierce the flesh, before rubbing in the marinade. Using some turf bring an Irish smokiness to the meat.
Preheat a gas barbecue to medium heat or a charcoal until white ashes forms on the glowing coal.
Place all the marinade ingredients into a food processor or a pestle and mortar.
Combine until the mixture has a coarse consistency. Transfer the mixture into a large bowl and coat the racks of lamb all the way through. You can marinate overnight if desired.
Add a piece of turf into the barbecue ashes if using charcoal barbecue.
Place the rack of lamb onto the barbecue and grill for 5 minutes over direct heat. Move into a indirect heat or cooler part of the barbecue and continue to grill for a further 20 minutes or until cooked to your liking.
Just before serving, add the asparagus onto the barbecue. Season with salt and pepper and cook for 3-4 minutes until charred. Remove from the barbecue and place on a serving platter with the racks of lambs. Let the meat settle for 3-5 minutes.
Carve and serve with the asparagus and some salad leaves with some balsamic dressing.