In a large dutch oven, heat 1 tbsp of oil over medium-high heat. Season beef with salt, pepper and thyme, and then toss in the pot to brown. When browned, remove beef to a plate and set aside.
Add 1 tbsp oil and lower to medium heat. Add in onions, celery and carrots, stirring regularly, for about 5 minutes or until the onions start to go translucent. Add mushrooms and garlic, and continue to cook for about 5 minutes or until the mushroom liquid starts to evaporate
Stir in beef and any juices from the plate. Add broth, barley, tomato paste and bay leaf. Bring to a boil, then reduce heat to low. Cover and simmer for an hour, or until beef and barley are tender. Stir occasionally and add water if the soup becomes too thick. Discard bay leaf before serving.
Recipe by Life at Cloverhill at https://lifeatcloverhill.com/2011/11/mushroom-beef-barley-soup.html