3large purple eggplant170 mlolive oil40 gmtahini3cloves of garlic, finely chopped2lemons, finely grated rind and juice only½ tspground cumin¼ tspground chilli2 kgboned, butterflied leg of lambFor brushing:extra-virgin olive oil2Spanish onions, cut into wedges1cup each of (loosely packed) flat-leaf parsley and mint leaves250 gmfine burghul, soaked in cold water for 20 minutes, drained (see note)400 gmcanned chickpeas, drained and rinsed
Cook 2 eggplant over an open flame, turning frequently, until charred and soft (7-8 minutes). Transfer to a colander to drain juices, cool, then peel. Place in a food processor with 60ml olive oil, tahini and half the garlic and half the lemon juice and process until smooth. Season generously with sea salt and freshly ground black pepper. Thin with a little hot water, if necessary, and stand at room temperature until required.
Preheat oven to 190C. Cut the remaining eggplant into 1cm dice. Combine in a bowl with 60ml olive oil, cumin, chilli, half the lemon rind and remaining garlic. Season generously, then transfer to a roasting pan and roast until golden and tender (about 15 minutes).
Open out lamb leg on a clean work surface, scatter over roasted eggplant and remaining lemon rind. Season to taste, then roll tightly to form a cylinder and tie at intervals with kitchen twine. Brush with a little extra-virgin olive oil and season to taste.
Scatter onion wedges over base of a small roasting pan, place lamb on top and roast until medium-rare (about 1 hour, 20 minutes) or until cooked to your liking. Cover loosely with foil and rest for 10-15 minutes, then thickly slice.
Transfer onion to a bowl, add herbs, burghul, chickpeas, remaining lemon juice and remaining olive oil. Season to taste and toss to combine. Serve with sliced lamb and baba ghanoush.
Note Burghul, also called cracked wheat, is available from select supermarkets, delicatessens and health food stores.