Heat the oven to 200°C/fan 180°C/gas 6. Line a baking tray with baking paper.Put the onion, ginger, curry paste, curry leaves and stock in the slow cooker. Add the cauliflower, kumara and tomatoes and stir. Cover and cook on low for 3–4 hr until tender.
Stir in the yoghurt, lentils, spinach, peas, courgette and half the coriander. Turn the slow cooker setting to high. Cover and cook the mixture for a further 30 min.
Serve on a bed of rice, garnished with the remaining coriander.