Pat the beef dry and season with salt and pepper.
Heat olive oil in a Dutch oven over medium-high heat. Sear the beef in batches until deeply browned. Transfer to a plate.
Reduce heat to medium. Add onion, carrots, and celery and cook for 5–6 minutes until softened.
Add garlic and tomato paste. Cook for 1–2 minutes.
Pour in ½ cup beef broth and scrape the browned bits from the bottom of the pot.
Return the beef and its juices to the pot. Add remaining broth, bay leaves, thyme, remaining salt, and pepper.
Bring to a gentle boil, reduce heat, partially cover, and simmer for 45–50 minutes, or until the beef is beginning to become tender.
Stir in rinsed pearl barley.
Continue simmering partially covered for 30–40 minutes, stirring occasionally, until the barley is tender and the beef is fork-tender.
Remove the bay leaves. Taste and adjust seasoning.
Add additional broth or water if the soup is too thick.
Serve hot with fresh parsley.