1.Make tandoori paste; reserve 2 tablespoons in a small bowl. Dry-fry seeds in a heated medium frying pan, stirring, until fragrant. Blend or process seeds with remaining ingredients until smooth.
2.Combine lamb with remaining paste in a large bowl; turn to coat all over in paste. Cover; refrigerate 1 hour.
3.Cook lamb on a heated oiled barbecue until browned all over. Place lamb in a deep disposable baking dish; cook in a covered barbecue, using indirect heat, following manufacturer’s instructions, about 35 minutes or until cooked as desired. Remove from barbecue; cover with foil, rest 15 minutes.
4.Meanwhile, cook eggplant on heated oiled barbecue, brushing with reserved tandoori paste, about 10 minutes or until eggplant is tender. Cover to keep warm.
5.Make cucumber and mint raita. Heat oil in a small frying pan; cook seeds and garam masala, stirring, over low heat, 2 minutes or until seeds pop. Combine spices and remaining ingredients in a medium bowl.
6.Toast naan both sides on heated oiled barbecue. Serve lamb with eggplant, naan and raita.