Heat the olive oil in a large saucepan over medium-high heat. Add onion, and sauté for 3 minutes. Add rice, and sauté for 1 minute. Stir in the water and broth, and bring to a boil. Cover, reduce heat to medium-low, and cook for 45 minutes or until the liquid is absorbed. Spoon into a large bowl; fluff with a fork. Add tomato and remaining ingredients, and toss well. Serve at room temperature or chilled.