Preheat the oven to 180°C or 350°F.
In a food processor, pulse cauliflower into couscous-sized grains and spread thinly on a baking tray. Roast for 15-20 minutes (stir after 10). Allow to cool. In a bowl, combine cauliflower with all other couscous ingredients and stir thoroughly.
Increase oven to 220°C or 430°F. Season lamb generously with salt and pepper, then sprinkle each rack with ½ the cinnamon and olive oil. Place frying pan over high-heat. Place both lamb racks fat-side down and allow to colour. Sear each of the remaining sides then place in oven for 10 minutes (3). Allow to rest for 5 minutes before slicing into cutlets.
Serve cutlets with couscous and a touch of harissa on each plate and garnish with reserved mint leaves.