Place the lamb mince, fresh coriander, half the garlic, 2 teaspoons ground cumin and 1 teaspoon each ground coriander and smoked paprika into a bowl and mix thoroughly to combine. Season to taste with salt and pepper. Roll into small walnut size balls.
Heat olive oil in a frying pan over medium high heat. Cook the meatballs for 3-5 minutes or until lightly browned all over. Remove with a slotted spoon and set aside on a plate. Drain off excess fat in pan, leaving at least 1 tablespoon.
Add the onion to pan and cook for 5 minutes or until softened. Then add the remaining garlic, cooking for 1 minute. Add the harissa, cinnamon stick and remaining spices, cook stirring for 2 minutes. Add chickpeas, passata and 1 cup water. Season to taste with salt, pepper and caster sugar, if using.
Return meatballs to sauce, bring to the boil, then reduce heat to very low and simmer for 20 minutes or until meatballs are cooked through and sauce has thickened slightly. Serve with buttered couscous and garnish with extra coriander, a dollop of yoghurt and some lemon wedges.