The lamb should go into its marinade ideally 2 nights prior though one night will do apparently- I did 2 nights prior so would strongly recommend.
Remove all the fell (parchment like outer skin) and fat from the lamb.
Jab the lamb all over with a sharp knife.
Put all the yoghurt in a big bowl or deep tray (big enough to hold your lamb leg).
Take around 4 tbsp of the yoghurt and put in the blender then add the chopped 1/2 onion, the garlic, ginger, salt, cayenne and garam masala.
Blend until you have a smooth paste.
Pour the contents into the bowl of yoghurt and mix well.
Put the leg of lamb into the yoghurt and rub the marinade into the meat.
Cover well and refrigerate for 24 - 48 hours.
You should start cooking the lamb around 3 1/2 hours prior to serving Preheat oven to 180 degrees Take a heavy roasting tin. Put the lamb at the centre and pour the marinade on and around it.
Bring to a simmer on top of the stove.
Cover tightly with aluminium foil and put in the oven.
Bake, covered, for 1 1/2 hours.
While the lamb bakes, set a cast-iron frying pan over medium heat. When hot put in the almonds- stir around until they have roasted lightly. Now grind them in a clean coffee-grinder or other spice-grinder .
Add the almonds to the lamb sauce after 1 1/2 hours and mix well. When adding the almonds, also scatter the figs around the leg.
Cover again, put the lamb back in the oven and bake for another 1 - 1 1/2 hours.
While the lamb is baking fry the onions. Line a plate with kitchen paper and fry onions in the oil until they start to brown around the edges. Allow onions to drain on the plate.
Roast the poppy seeds in a heavy based frying pan- aim is for it to be a couple of shades darker. Remove the seeds and allow to cool. Grind as finely as possible in a coffee or spice grinder.
When the lamb is tender, crumble the onions and add them as well as the ground poppy seeds to the lamb sauce.
Spoon some of this sauce over the lamb and put back in the oven for 10 minutes.
To serve, I scooped out most of the (divine!) sauce and served separately with the lamb and figs on a plate for the lamb to be carved.
Carve the meat at the table.
(Serving recommendation: I served with Green Beans with Ginger and Coriander, Dry Potatoes with Garlic and Ginger, Yellow Rice, Raita and some bought chutneys)