Heat the olive oil in a large pot or Dutch oven over medium-high heat.
Add the beef stew meat and cook until browned on all sides, about 5–7 minutes.
Remove the beef from the pot and set it aside.
In the same pot, add the diced onion, carrots, and celery.
Cook for 5 minutes, stirring occasionally, until the vegetables begin to soften.
Add the minced garlic and cook for another 1–2 minutes until fragrant.
Return the browned beef to the pot.
Add the beef broth, barley, bay leaves, and thyme. Stir to combine.
Bring the soup to a boil, then reduce the heat to low.
Cover and simmer for about 45 minutes, or until the barley is tender and the beef is fully cooked.
Remove the bay leaves and season the soup with salt and pepper to taste.
Serve hot with a slice of crusty bread.