Stir in tomatoes, broth, reserved lentil cooking water, and lentils, and bring to a boil. Cover, reduce heat to low, and cook 20 minutes, or until liquid is absorbed and rice is tender. Season with salt and pepper. Remove from heat, cover, and let stand 5 minutes. Fluff with fork, then spoon pilaf into shallow bowls, and garnish with cilantro if desired. Serve hot.