Heat olive oil in a large pot or Dutch oven over medium-high heat. Brown the beef in batches, then set aside.
Add onion, carrots, and celery to the pot and cook until softened, about 5 minutes. Add garlic, thyme, and rosemary and cook for 1 minute more.
Return the beef to the pot. Add beef broth and barley. Bring to a boil, then reduce heat and simmer for 60-75 minutes, or until the beef is tender and the barley is cooked.
Season with salt and pepper to taste. Serve hot.
Notes
This soup is even better the next day! Store leftovers in the refrigerator for up to 3 days.