Taken from the wonderful book Made In India by Meera Sodha. This is a great simple way to make basmati rice that's just a little bit fancier than plain rice and will go well with so many Indian dishes.
Add your oil to a nonstick pan (you'll also need a lid that fits this pan) on medium heat.
Fry the onion in the oil for 12-15 minutes until nicely browned and caramelized.
Add the cumin seeds and salt to the onions.
Drain the rice and add to the onion mixture, stirring to coat all the rice grains in some oil if possible.
Pour the boiling water over the rice, give it a stir, then put the lid on the pan and bring to a rolling boil.
After 2 minutes, drop the heat to a simmer and cook for 10 additional minutes, never removing the lid.
Remove from the heat and rest for 10 minutes, then serve optionally with butter if you want it a bit more rich or just on its own.