In a medium saucepan, combine the rice and water, bring the mixture to a boil, reduce the heat, cover the pan, and simmer the mixture for 20 minutes (35 minutes for brown rice). Keep the pan covered until the vegetable mixture is done.
Meanwhile, heat the oil in a large skillet, add the onion and garlic, sauté them until they are soft.
Add the tomatoes, zucchini, and oregano. Cover the skillet, and simmer the mixture for about 5 minutes or until the vegetables are tender-crisp.
Add the beans, and simmer the mixture, stirring it occasionally, until it is heated through. Season with salt if desired, and pepper.
To serve, spoon the vegetable-bean mixture over the hot rice, and sprinkle the cheese on top.