For the Keralan curry, put the turmeric, yoghurt and a pinch of salt in a bowl and mix well. Add the chicken pieces and leave to marinate for an hour.
Meanwhile, make the curry paste. Place a frying pan over a low heat and add the oil, followed by the ginger and garlic. Fry for about a minute, then add the remaining paste ingredients and fry for 5–6 minutes, or until lightly coloured. Leave to cool, then transfer to a blender, add 3–5 tablespoons water and blend to a fine paste. Set aside.
To finish the Keralan chicken curry, place a heavy-based, non-stick pan over a medium heat and add the vegetable oil. When hot, add the chillies and let them sizzle for about 10 seconds. Add the onion and a pinch of salt and fry for 10–12 minutes, or until browned. Stir in the blended tomatoes and cook for 3 minutes. Add the spice paste and fry for 4–5 minutes, stirring well, until the sauce thickens slightly. Increase the heat and add the marinated chicken pieces, stirring well to coat them with spice paste. Fry for 4 minutes, or until lightly coloured. Add 100ml/3½fl oz water and season with salt and pepper. Cover with a lid and simmer for 25 minutes, or until the chicken is cooked through. Add the coconut milk, stir well and simmer for a further 4–7 minutes, or until the sauce is slightly thickened.
For the raita, in a small bowl, add the mint, coriander, yoghurt, ginger, spring onions and 100ml water to a blender. Blend to a smooth paste, then transfer to a bowl and sprinkle over the crushed cumin seeds, black salt and sea salt. Set aside.
For the lime and coriander rice, season the cooked rice with salt and pepper. Fork lightly to loosen the grains and set aside.
Place a large heavy-based saucepan over a medium heat and add the oil. When hot, add the chopped chilli and fry for a few seconds. Add the rice and heat through, stirring well. Add the lime zest and fresh coriander. Mix well and turn off the heat. Stir through the lime juice.
To serve, garnish the curry with chilli flakes or coriander and serve in bowls with the rice and raita alongside.