Take the lamb out of the fridge an hour or so before cooking to allow it to come up to room temperature. Heat oven to 220C/200C fan/gas 7 or light the barbecue. Mix together the oil, caraway seeds, thyme and parsley with lots of salt and pepper. Smear this all over the lamb, rubbing it well into the meat. You can do this up to a day before.
If you are cooking the meat on the barbecue, wait until the fire has died down and the coals are white and glowing. Lay the meat, skin-side down, onto the bars and cook for 15 mins. Flip over and cook for a further 15 mins for slightly pink lamb, or 5 mins longer if you want the meat well done. Remove and leave to rest on a tray, covered with foil, for at least 15 mins. To cook the lamb in the oven, place it on a large shallow baking tray, cook for 15 mins, then turn down the oven to 180C/160C fan/gas 4 and cook for a further 15 mins. Leave to rest for 15 mins. Once the meat has rested, slice it up and pour over any juices from the resting tray.