In a medium soup pot, heat the 2 tablespoons of olive oil. Add the onion and cook over moderate heat until softened, about 5 minutes. Add the carrots, celery and garlic and cook, stirring occasionally, until tender, about 5 minutes. Add the water, tomatoes with their juices, lentils, bay leaves and rosemary. Bring the soup to a simmer, breaking up the tomatoes with the back of a spoon. Cover and simmer over low heat until the lentils are tender, about 30 minutes. Season the soup with salt and pepper and discard the bay leaves and rosemary sprig. Ladles the soup into bowls, drizzle with olive oil, sprinkle with cheese and serve.