In a large sauce pan, warm oil on medium-high heat.
Add the beef and cook for 5 minutes, or until evenly browned. Remove with a slotted spoon and reserve.
Add the onion, celery, and carrots and cook for 5 minutes or until soft.
Add the red wine, garlic, and thyme and reduce by half.
Add the seared beef, stock, and barley and bring to a boil.
Reduce to a simmer, cover, and cook on low heat for 1½ hours.
Add the mushrooms and cook for 10 minutes or until the beef is very tender.
Season with salt and pepper and serve in warmed bowls.