- Heat the olive oil in your Dutch oven over medium-high heat. Add the beef stew meat cubes and brown them on all sides, about 5-7 minutes. Remove the beef and set aside. 
- In the same pot, add the chopped onion, diced carrots, and celery. Sauté until the vegetables soften, about 5 minutes. Stir in the minced garlic for the last minute until fragrant. 
- Return the browned beef to the pot. Add dried thyme, bay leaf, diced tomatoes, beef broth, and water. Stir to combine and bring to a gentle boil. 
- Once boiling, reduce heat to low and cover the pot. Let the soup simmer for about 1 hour, or until the beef is tender. 
- After the beef has softened, stir in the barley. Continue simmering the soup, uncovered, for an additional 30-40 minutes, or until the barley is tender and the soup has thickened slightly. 
- Remove the bay leaf, then taste and season with salt and pepper as needed. Serve hot with crusty bread or a simple green salad.