Heat olive oil in a large pot over medium heat.
Add diced onion, carrots, and celery; sauté until softened, about 5-7 minutes.
Stir in minced garlic and dried thyme; cook for another minute until fragrant.
Add the beef pieces; cook until browned on all sides, about 5-10 minutes.
Pour in the beef broth and add bay leaf, salt, and pepper; bring to a boil.
Reduce heat to low, cover, and simmer for 1 hour.
After one hour, stir in the pearl barley; continue to simmer for another 30-40 minutes.
Taste and adjust salt and pepper as needed before serving.
Remove the bay leaf and serve hot, garnished with fresh parsley if desired.