1. Pat the beef cubes dry and season them with salt and black pepper. Heat 1 tablespoon olive oil in a large Dutch oven over medium-high heat. Brown half the beef for 6-8 minutes, transfer it to a plate, then repeat with the remaining beef and oil.

2. Reduce the heat to medium. Add the onion, carrots, and celery. Cook for 5-6 minutes. Add the mushrooms and cook for another 4-5 minutes.

3. Stir in the garlic and tomato paste. Cook for about 1 minute, stirring constantly.

4. Pour about 1 cup beef broth into the pot. Scrape the browned bits from the bottom with a wooden spoon.

5. Return the browned beef and accumulated juices to the pot. Add the remaining beef broth, Worcestershire sauce, thyme, and bay leaves. Bring to a gentle boil.

6. Reduce the heat to low, partially cover the pot, and simmer for approximately 45 minutes.

7. Stir in the rinsed pearl barley. Gently simmer for another 40-50 minutes, stirring occasionally, until the barley becomes tender and pleasantly chewy and the beef becomes fork-tender.

8. Add 1-2 cups hot water or additional beef broth if the barley absorbs too much liquid.

9. Remove the bay leaves. Taste and adjust the salt, black pepper, or Worcestershire sauce as needed.

10. Turn off the heat and rest the soup for 10 minutes. Stir in half the fresh parsley and garnish each serving with the remaining parsley.