- Heat oil in 4-quart saucepan over medium-high heat. Add onion and celery; cook and stir 5 minutes.
- Add mushrooms and cook, stirring, over high heat 5 minutes.
- Add 1/4 cup soy sauce, bay leaf, thyme and 5 cups water. Bring to boil; stir in barley. Cover and simmer about 50 minutes, or until barley is tender.
- Remove bay leaf. Stir in chives; simmer 5 minutes longer.
- Remove from heat; stir in remaining 1 Tbsp. soy sauce. Season with pepper, if desired.