Heat oil in a large saucepan over medium heat. Saute cumin seeds and cloves for less than 1 minute. Saute the onion, stirring constantly, until brown. Stir in rice and fry for about 1 minute, stirring. Stir in the water, salt, garam masala, chili powder and vegetables. Bring to a 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.