In a large saucepan, heat 1 tablespoon oil over medium heat. Add onion and thyme, cover pan, and reduce heat to low. Cook until onion is soft, about 6 minutes. Add broth, bay leaf, and barley; bring to a boil, reduce heat, and simmer, covered, until barley is tender, about 15 minutes.
Meanwhile, heat remaining oil in skillet over high heat. Add half the beef and cook, stirring occasionally, until browned. Using a slotted spoon, transfer to a bowl. Add remaining beef to skillet and cook to brown. When barley is tender, add beef and vegetables to soup, and cook 5 minutes longer, until vegetables are tender.