Set the oven to 240*.
Toast the whole spices in a medium hot dry pan, added the ground spices as the pan is taken off the heat, cool and grind in a mortar and pestle. Add the garlic and grind again.
Fold through the yoghurt, season with the lemon juice, salt and pepper.
reheat in the oven before carving if necessary.
Remove any excess fat from the lamb and score deeply to help the marinade soak in.
Coat the lamb liberally with the marinade and allow to marinate for at least 2 hours.
heat a roasting tray with a cooling rack or a tinfoil trivet.
Add a handful of wet straw to the bottom of the tray to create a smokey infusion to the oven.
loosely cover the leg of lamb in tinfoil and bake for 30 minutes.
take off the tinfoil and bake for a further 40-60 minutes depending on the size of the leg and the degree of cooking required.
Skewer the lam leg with a temperature probe, for pink lamb the probe should read around 58 degrees celcius, take out and rest the meat for a further 20 minutes before serving,
Serve sliced with rice or other traditional accompaniments
«Resting the meat is very important to prevent toughness and to retain moisture. The marinade should crisp and caramelise, if this happens to quickly cover with tinfoil. Garlic powder can be substituted for fresh garlic, which keeps the marinade drier»