Preheat oven or kettle barbecue to 160°C. Rub lamb with oil. Brown lamb in large non-stick frying pan or on barbecue. Sprinkle cumin on browned lamb and season with freshly ground black pepper.
Place chopped onion, carrot and garlic in baking dish or disposable foil baking tray. Place lamb on top. Cover with foil and bake in oven or bbq for 3 hours. Place lamb on warm platter and lightly cover to rest for 20 minutes. Drain cooking juices through sieve, discard the vegetables. Spoon off or remove fat (see tip) and place liquid in large frying pan. Cook over high heat until reduced to ½ cup (125ml) of liquid. Add quince paste or jelly, if using, and stir until combined.
Thickly slice with lamb, drizzle with sauce. Serve with herb salad.
Tip: If you pour the cooking juices over a big bowl of ice cubes then the fat will cling to the ice. Discard fat-coated ice.
Place parsley, mint leaves and coriander in a bowl. Stir in the tomatoes, cucumber and radishes. Whisk together oil and pomegranate molasses (or lemon juice). Gently toss through salad.