Heat the olive oil in a large pot or Dutch oven over medium heat.
Add the diced beef and brown on all sides, about 5-7 minutes. Season with salt and pepper.
Add the chopped onion, carrots, celery, and garlic to the pot. Sauté for another 5 minutes, until the vegetables are slightly softened.
Stir in the barley, thyme, rosemary, and undrained diced tomatoes. Mix well to combine.
Pour in the beef broth and bring the mixture to a boil.
Reduce the heat to low, cover, and let it simmer for about 1 hour, or until the beef is tender and the barley is cooked through, stirring occasionally.
Adjust seasoning with salt and pepper as necessary. If the soup is too thick, add a little more broth or water until the desired consistency is reached.
Serve hot, garnished with fresh parsley if desired.