Heat the vegetable oil in a large, lidded, heavy-bottomed pan over a medium heat. Fry the coconut paste for 2-3 minutes. Add the chilli powder, turmeric and spice mixture. Fry for 1 minute, stirring well. Turn up the heat slightly and add the chicken pieces. Fry for 5 minutes, mixing well as the chicken cooks. Season and add 400ml of water, bring to a boil and simmer over a low heat for 25 minutes with the lid on, stirring halfway. Add the coconut milk, remove the lid and simmer for another 15-20 minutes or until the sauce has thickened and the chicken is tender. Stir in the lime juice and serve with chapatis or naan breads, if you like.