1. Season the lamb shoulder very well with the salt and pepper. Combine the yoghurt, garlic, ginger and spices and rub all over the lamb. Marinate overnight in the refrigerator.

2. Heat your oven to 160C fan-forced (180C conventional). Cut two of the onions into quarters and place them in the base of a lidded pan or roasting tray. Put the lamb on top and add a cup of water. Cover with a lid or aluminium foil and roast for 4 hours. Uncover the lamb for the last hour of cooking to brown the meat and onions. Use the grill setting if the lamb is not browned to your liking. 

3. For the chutney, combine all the ingredients except the yoghurt in a blender and blend to a smooth paste, adding a little water if necessary. Swirl through the yoghurt. 

4. Finely slice the remaining red onion and scatter over the lamb with extra mint and coriander leaves. Serve with lemon wedges and the chutney, and accompany with rice, naan or flour tortillas if you like. 

Also try Adam Liaw's cinnamon bread and butter pudding