To make the garam masala, put all the ingredients in a dry pan over medium heat, shaking the pan to toast the spices evenly.
Cool the spices for a minute and tip them into an electric blender and grind to fine powder, or use a pestle and mortar. Pass through a sieve and set aside.
To cook the chickpeas, drain away the soaking water. Put the chickpeas in a pan of clean water with the bay leaf, cardamom, clove and salt and boil until cooked. Set aside until required.
For the sauce, in a clean pan heat the oil and gently fry the cloves, bay leaf and black cardamom. Add the onions and cook until translucent. Add the ginger-garlic paste and cook well. Add dried powdered spices, salt, tomatoes and enough water to cover the mixture add the chickpeas and simmer for 30 minutes, or until the gravy thickens.
For the lamb, turn the oven down to 200C/180C Fan/Gas 6.
Sear the rump on a hot pan to colour it on all sides. Dust the rump with the garam masala mixed with salt. Roast in the oven for 5-7 minutes, remove and rest for 3-4 minutes then slice.
In a bowl, mix together the garnish ingredients.
Put the chickpeas on a serving dish and sit the sliced lamb on top. Top with the garnish and serve hot with naan bread.
The recipe makes more Punjabi garam masala spice mix than you will need, but the extra can be kept sealed in a jar for 2-3 weeks.