In a large saucepan over medium heat, heat the olive oil. Add the onion and cook, stirring frequently, until tender, about 5 minutes. Raise the heat to medium-high and add the barley. Cook, stirring constantly, for 1 minute. Stir in half of the remaining vegetables and cook for 1 minute more. Add all the broth and bring to a simmer. Cover and cook for 20 minutes. Add salt, pepper and the remaining vegetables. Cook, uncovered, for 10 minutes more, or until the liquid has evaporated and the barley is tender. Remove from heat. Stir in the cheese and serve immediately.