Set out a large bowl of iced water. Put the rice and water in a small saucepan and bring to the boil. Stir once, then reduce the heat to low and cover the pan. Cook for 15 minutes. Remove from the heat and leave to stand, without removing the lid, for 10 minutes.
Meanwhile, preheat the oven to 200 degrees C. Trim off the tough stalk from the base of each cabbage leaf. Bring a large saucepan of water to the boil. Add half the leaves, bring back to the boil and blanch for 30 seconds. Remove the leaves and plunge them into the bowl of iced water to stop them cooking. Repeat with the remaining leaves. Drain the leaves well and spread out on a tea towel to dry.
Heat the sunflower oil in a large frying pan and sauté the onion for about 3 minutes or until softened. Add the cumin seeds and ground coriander and cinnamon, then cook for a further 2–3 minutes. Remove from the heat.
Add 2 tablespoons of the mango chutney to the onion mixture, together with the cashews, well-rinsed lentils, turkey or chicken, parsley and pepper to taste, then mix thoroughly. Stir in the rice until thoroughly combined.
Lay a cabbage leaf flat on the work surface, with the stalk end towards you. Place some of the rice mixture on the leaf. Fold the base of the leaf over the filling, then fold in the sides and roll up the leaf to enclose the filling in a neat parcel. Repeat with the remaining leaves and filling.
Mix the remaining 1 tbsp of mango chutney with the tomato juice. Pour about one-quarter of this sauce into a large baking dish. Pack the cabbage parcels into the dish and pour the rest of the sauce over them. Cover loosely with foil and bake for about 30 minutes or until the leaves are tender. Garnish with parsley.