Season the beef with salt and pepper to taste. Turn the Instant Pot to saute and heat the oil. Working in batches, brown the meat well on all sides, about 4 to 5 minutes per batch. With a slotted spoon, transfer the beef to a bowl.
Add the onions, carrots, celery and mushrooms and cook for about 4 minutes or until the onions begin to soften. Stir in the garlic and cook for about 1 minute.
Pour the wine into the pot to deglaze it. Using a wooden spoon, scrape up the browned bits stuck to the bottom of the pot. Simmer for about 2 minutes then press cancel.
Return the beef and any collected juices to the pot. Add the barley, thyme, bay leaf, stock, Worcestershire, tomato paste and bouillon (if using) to the pot. Stir to combine. Cover, seal the lid and cook on high pressure for 30 minutes. When done, let the pressure release naturally for 15 minutes and then release the remaining pressure manually. Discard the bay leaf and thyme sprigs. Taste and season with salt and pepper, if needed.
Ladle the soup into individual bowls, and garnish with parsley.