Heat oil in a large Dutch oven over medium heat. Add onion; cook 5 minutes or until slightly soft. Remove casings from sausage. Add sausage to pan; cook 8 minutes or until sausage is browned, stirring to crumble. Add celery, carrot, garlic, and bay leaf; cook 10 minutes or until onions are golden brown, stirring frequently. Stir in mushrooms; cook 10 minutes or until mushrooms release moisture. Stir in barley, chicken broth, brandy, salt, and pepper. Bring to a boil; cover, reduce heat, and simmer 1 hour or until barley is tender. Discard bay leaf. Sprinkle with parsley. Serve immediately.