1.Preheat oven to 200°C/400°F. Oil 2-litre (8-cup) ovenproof dish.
2.Finely grate rind from lemon, you need 2 teaspoons. Squeeze juice from lemon, you need 2 tablespoons. Blend or process coriander, 2 tablespoons of the oil, juice, garlic and spices until smooth.
3.Combine spice paste, stock and kumara in large bowl; season. Transfer mixture to dish. Cover with foil; bake 1 hour 10 minutes. Remove foil; sprinkle with combined breadcrumbs, parsley, lemon rind and remaining oil. Bake, uncovered, about 20 minutes or until sweet potato is tender. Stand 5 minutes before serving.