To make the lamb, add all the ingredients (exept the lamb) in a bowl and stir to combine. Score the lamb about 1/2 slits on the fat side and meat side. Rub the marinate all over the lamb, making sure to get in the slits you made. Place it in a bowl and allow it to marinate in the fridge for at least 6 hours or over night.
When ready, take the lamb out of the fridge and allow it to sit at room temperature for abotu 20 minutes. Use kitchen twine to wrap the uneven parts of the meat and make it a more uniform shape.
If using a rotiserrie, follow manufactures instructions. It took about 2 hours for our lamb to cook.
If using the oven, place lamb in an oven proof dish with fat side up. And roast at 325 degrees F for about 4 1/2 hours.
After 30 minutes of cooking, add 1 cup of hot water to the pan and baste about every hour.
The last 3 hours, cover the pan with foil so the rub doesn't burn.
When done, the meat should fall apart easily and read 160 degrees F using a meat thermometer. Allow the meat to rest for 10 minutes before slicing.