Heat water in medium saucepan over medium-high heat to a boil. Add barley. Reduce heat to medium-low. Cover and cook for 40 minutes, or until barley is tender, stirring occasionally. Drain.
Cook beef in 3-quart nonstick saucepot until well browned, stirring often. Add mushrooms and garlic and cook until mushrooms are tender.
Stir in broth, thyme, black pepper and carrots. Heat to a boil. Reduce heat to low. Cover and cook for 10 minutes, or until carrots are tender. Stir in barley.
Tip: Substitute 1/2 cup quick-cooking barley for pearl barley. Cook for 12 minutes (or according to package directions), or until barley is tender.