In a large saucepan, heat 2 tablespoons olive oil over medium heat. Add the onion and cook until translucent, about 6 minutes. Stir in the broth and barley and bring to a boil. Lower the heat, cover and simmer until the barley is tender, 30 to 40 minutes. Stir in the white beans and simmer for 5 minutes. Season with pepper, stir in the parsley and serve.