Heat the oil over medium high heat in a 1 qt. or larger saucepan with a lid. Peel and coarsely chop the onion and add it to the pan. Stir and cook for 3 minutes or until onion starts to brown on the edges. Add water and raise the heat to high. Cover the saucepan and bring the water to a boil. When the water boils, add the rice, frozen vegetables and the marinade to the pan. Stir well, cover and reduce heat to low. Simmer for 5 minutes or until liquid is absorbed and rice is tender. Serve immediately or cover, remove from the heat and let rest for up to 15 minutes.