Sprinkle the lamb with the chili
powder and half the lime juice.
To make the marinade, combine the
yoghurt, onion, garlic, ginger, remaining lime juice, cayenne
pepper, cumin, coriander, turmeric, cinnamon and sea salt.
Place the lamb in a large
non-metallic dish and cover it with the marinade.
Turn to coat well, cover and
refrigerate overnight.
Preheat the oven to moderately hot
200C (Gas 6).
Bring the meat to room temperature, then roll up and tie at intervals with string.
Roast for about 90 minutes for medium-well done, basting regularly with the marinade.
Rest for 15 minutes.
Remove the string and carve into slices.
To make pilau: heat the oil in a large saucepan and add the onion.
Cook for 5-6 minutes over medium heat, or until soft.
Add the rice and cook for 2 minutes, then add the stock and bring to the boil.
Reduce the heat, cover with a lid and simmer for 15 minutes, or until all the liquid has been absorbed and rice is tender.
Stir in the mint and season to taste with salt and pepper.