Toss stew beef pieces with the flour, 1/2 teaspoon salt, and 1/8 teaspoon pepper. Add to the bacon mixture. Add olive oil. Add mushrooms, celery, and onion. Cook over medium heat, stirring frequently, until beef is browned and onion is tender. Add beef broth and bay leaf. Cover and simmer over medium-low heat for 45 minutes. Add barley, carrots, and turnip. Reduce heat to low. Cover and simmer for 25 minutes. Add potatoes and simmer for about 25 minutes longer, or until vegetables and meat are tender. Add peas and cook for 10 minutes longer.