1.Place chickpeas in large bowl of cold water; stand overnight. Drain.
2.Cook chickpeas and bay leaf in medium saucepan of boiling water, uncovered, until just tender; drain. Rinse under cold water; drain.
3.Meanwhile, place lamb, 2 tablespoons of the oil and combined sumac, seeds, dried herbs and paprika in large bowl; toss to coat lamb. Cover; refrigerate 30 minutes.
4.Make sumac dressing. Combine ingredients in screw-top jar; shake well.
5.Heat butter and remaining oil in large frying pan; cook onion, stirring, about 10 minutes or until browned lightly and softened. Add carrot, celery and fennel; cook, stirring, until vegetables are just tender.
6.Meanwhile, cook lamb, in batches, on heated oiled grill plate (or grill or barbecue) until browned and cooked as desired. Cover; stand 5 minutes. Slice lamb thickly.
7.Just before serving, combine chickpeas, parsley and half of the dressing with vegetables; cook, stirring, until heated through. Divide chickpea salad among serving plates; top with lamb, drizzle with remaining dressing.
Za’atar, a mixture of toasted sesame seeds, dried marjoram, thyme and sumac, can be found already blended in Middle-Eastern food stores. Alternatively, you can make your own blend, as we have here. Sumac, a purple-red, very astringent spice, adds a tart, lemony flavour to dips and dressings and goes well with barbecued meats.