Roughly chop 4 of the onions.
In a food processor or blender add the 4 chopped onions, garlic cloves and ginger with 1/4 cup of hot water. Blend until you have a thick paste. Set to one side.
Cut the remaining 6 onions into half moon slices.
Melt the ghee/oil in a large heavy bottomed pan and fry the onion moons. Use a medium-high heat. You want the onions to cook quickly and start to caramelize.
Using a slotted spoon to remove the onions from the pan and set aside for later.
Cut the lamb into bite size chunks and fry it all off in the onion flavoured ghee/oil.
Add your onion-garlic-ginger puree to the lamb pan, give it a nice stir to coat the lamb.
Cook over a low heat for 10 minutes, until the onion mixture has softened. Don't allow the mixture to color.
Stir in the ground cumin, ground coriander, ground turmeric, ground cinnamon, ground cardamom, cayenne pepper (if using) and stir together.
Pour in the stock and tomato paste, stir well and gently simmer, uncovered, for an hour.
Check the lamb is tender. If not give it 10-15 minutes more. If the sauce is looking too dry add an extra 1/4 cup of water.
Stir through your fried onion moons, the yoghurt/ coconut cream and garam masala. Then cook for a further 5 minutes.
Finish the curry with a squeeze of lemon juice and fresh cilantro.Serve with Easy Homemade Naan bread.