2 teacups of long grain rice (I use basmati)
2 teacups water
Put the rice in a sieve and pour boiling water over it, then let the cold tap run through it until the water runs clear. Leave to drain well.
Bring 2 cups of water to the boil with a little salt to taste. Add the drained rice, bring it to the boil and let it boil vigorously for 2 minutes. Cover the pan with a tight-fitting lid and simmer very gently for 20 minutes (I use a small Le Creuset casserole and put it in the Aga's simmering oven, but a slow hob would do fine). When the time is up the rice should be thoroughly cooked with little dimples all over its surface, and all the water will have been absorbed. Leave to rest for 10 minutes.
Claudia Roden gives variations involving adding melted butter or oil, but I leave my rice unenriched - it will be quite 'dry' and the grains fairly separate, so if you want something stickier this won't be for you, but it is a good method. The quantities above will serve 4-5 people.