1) Dice the fish into large pieces. 2) In a bowl, mix the yoghurt with the tandoori paste, then add the fish and toss to coat completely. 3) Cover with clingfilm and refrigerate for at least an hour, or overnight. 4) Make the salsa by mixing the lemons, tomatoes and chopped coriander together in a bowl. 5) Melt the butter in a pan, then add the spices and cook for a couple of minutes. 6) Add the rice, mix well and add water to a level 2cm above the rice. 7) Put on a lid and bring to the boil, then simmer for 20 minutes or until the water has evaporated. 8) Fork through and leave in a warm place. 9) Preheat the grill until very hot. 10) Grill fish on a greased baking tray for about 15 minutes, or until charred around the edges. 11) Drain off any liquid, then serve with the rice and a little pile of salsa.