Sprinkle the rack of lamb liberally with the avieh spice. Place in a pre-heated oven for 12-15 minutes until cooked pink. At the same time, coat the vegetables with a little oil and roast in the same oven until golden. Bring the milk and garlic to the boil in a saucepan. Rain in the polenta and cook, stirring continuously until the polenta leaves the sides of the plan clean. Add the pureed chickpeas, season to taste. Heat the meat stock with the coriander and mint, add the butter in small pieces, whisking consistently. To serve, dress a spoonful of polenta in each serving bowl, cut the lamb rack into cutlets, dress on the polenta. Add the vegetables to the sauce and carefully pour over the lamb. Serve immediately.