Put the onion, ginger, curry paste, curry leaves and stock in the slow cooker. Add the cauliflower, sweet potato and tomato and gently mix together. Cover and cook on low for 4–5 hours, or until all the vegetables are tender.
Stir in the yoghurt, lentils, spinach, peas, zucchini and half the coriander. Turn the slow cooker setting to high. Cover and cook for a further 30 minutes, or unt