01 - Heat olive oil in a large soup pot over medium-high heat. Add beef cubes and brown on all sides, about 5 minutes. Remove beef and set aside.
02 - In the same pot, add onion, carrots, celery, and mushrooms. Cook for 6 to 7 minutes until softened.
03 - Stir in minced garlic and cook for 1 minute until fragrant.
04 - Return browned beef to the pot. Add diced tomatoes with juices, diced potato, barley, beef broth, water, bay leaves, thyme, parsley, salt, and black pepper.
05 - Bring to a boil, then reduce heat to low. Cover and simmer for 1 hour and 15 minutes, stirring occasionally.
06 - Remove lid and simmer uncovered for 20 to 25 minutes, until beef and barley are tender and broth has thickened.
07 - Remove bay leaves. Adjust seasoning if needed. Serve hot, optionally garnished with fresh parsley.