In a large pot, heat a tablespoon of oil over medium heat.
Add the cubed beef and brown on all sides.
Remove the beef and set aside.
In the same pot, add the onion, carrots, and celery; sauté until softened.
Stir in the garlic and cook for an additional minute.
Return the beef to the pot and add the barley, broth, diced tomatoes, and thyme.
Bring the mixture to a boil, then reduce heat to low.
Cover and simmer for about 1 hour, stirring occasionally.
Season with salt and pepper to taste.
Serve hot, garnished with fresh parsley.