To make the curry paste, pound the ingredients in a mortar with a pestle until you have a fine paste. Or use a blender to process the ingredients, adding
Heat a wok until just smoking. Add the oil and, when hot, add the paste and stir-fry for about 5 minutes until fragrant. Add the coconut milk and the chicken and simmer gently until the chicken is cooked. Add the lime leaves, fish sauce and sugar and taste for balance. Remove from the heat, sprinkle with the basil and squeeze over the lime juice to serve.