1.Toss lamb in flour to coat, shake off excess. Heat half the oil in large frying pan, cook lamb, in batches, until browned. Transfer to 4.5-litre (18-cup) slow cooker.
2.Heat remaining oil in same pan, cook onion, garlic and ginger, stirring, until onion softens. Add allspice, cook, stirring, until fragrant. Add ½ cup of the stock, cook, stirring, until mixture boils.
3.Stir onion mixture into cooker with remaining stock, harissa, rind and chickpeas. Cook, covered, on low, 7 hours.
4.Season to taste, sprinkle casserole with mint.
suitable to freeze at the end of step 3.Note