In a large pot or Dutch oven, heat the olive oil over medium-high heat.
Season the beef with salt and pepper, then add it to the pot. Sear the meat for 3–4 minutes on each side until it’s browned. Remove and set it aside.
In the same pot, add the diced onion, carrots, and celery. Sauté for 5–7 minutes until softened.
Add the minced garlic and cook for an additional 1–2 minutes until fragrant.
Return the seared beef to the pot. Stir in the beef broth, diced tomatoes with juices, pearl barley, dried thyme, and the bay leaf.
Bring the mixture to a boil, then reduce the heat to low, cover, and let it simmer for 45–50 minutes, or until the barley and beef are tender.
Remove the bay leaf. Taste and adjust seasoning with additional salt and pepper if needed.
Ladle the soup into bowls and garnish with freshly chopped parsley.