Rinse the rice well, put it in a bowl, cover with cold water and leave it to soak for 30 minutes. Then drain and leave it in a sieve until required.
Put a kettle on to boil. Heat the oil in a large saucepan over a medium heat. When it is hot, add the mustard seeds and as soon as they begin to pop, add the chilli and let it blacken.
Add the rice and turmeric, reduce the heat and stir-fry for 2-3 minutes.
Add the lime zest, coriander and salt to taste, then add 475 ml of boiling water.
Return to the boil, then reduce the heat to very low, cover the pan with a tight-fitting lid and simmer for 10 minutes without lifting the lid. Remove the pan from the heat and leave it for 8-10 minutes. Freshly cooked basmati is quite fragile. Letting it rest ensures fluffy, dry grains.