Set Instant Pot to saute setting. When hot add in stew meat, olive oil and season with a little salt and pepper. Brown meat on all sides then remove and set aside. (about 5 minutes)
Add mushrooms and saute until nicely browned. (May need to add a little more oil) Add onion, celery, and carrot. Season with salt and pepper if desired and cook for about 5 minutes. Add in garlic and stir for 30 seconds.
Add a little beef broth to deglaze the bottom of the pan and be sure to scrape up all the browned bits to avoid the burn error. Add remaining broth, tomatoes, barley, potatoes, beef base, bay leaf, and thyme.
Place lid on Instant Pot and turn to the locking position. Set vent to sealing and cook on high pressure for 15 minutes. Let the Instant Pot do a natural release of pressure for 15 minutes then turn vent to release remaining pressure before removing lid.
What to serve with Beef and Barley Soup