Heat oil in a large pan over medium heat. Sauté cumin seeds and cloves for less than 1 minute. Sauté the onion, stirring constantly, until brown. Stir in rice and fry for about 1 minute, stirring. Stir in the water, salt, garam masala, chilli powder and vegetables. Bring to the boil, then reduce heat, cover and simmer for 20 minutes, or until all water is absorbed.
Fluff with a fork and stir in butter before serving.