Prepare a marinade by combining the garlic, ginger, thyme leaves, cumin, turmeric and olive oil in a bowl.

Season the lamb with sea salt and black pepper, then drizzle with the marinade and rub all over the meat. 

Place on a roasting dish.

Place in the fridge for at least an hour and up to overnight for all the flavours to penetrate the meat.

Preheat the oven to 400 degrees and pour one liter of boiling water on the bottom of the roasting pan.

Cook the lamb for one hour to one hour and 15 minutes until golden brown and cooked through.

When the lamb is cooked to your liking, remove from the oven and leave to rest for 15 minutes.

Carve and serve with the pan juices left at the bottom of the roasting dish.