Set Instant Pot to Sauté. Add olive oil to Instant Pot, then cook beef until browned on all sides, for about 5 to 6 minutes.
Add in the onion and garlic, and cook for 3 to 4 minutes, stirring occasionally, until tender. Press Cancel.
Add in the butternut squash, mushrooms, beef broth, thyme, salt & pepper, and barley. Lock the lid and cook on high pressure for 16 minutes. Use quick-release method to release pressure. If soup gets too thick, add additional water or stock. Serve warm and enjoy!
Slow Cooker:
In a large Dutch oven, over medium high heat, warm 2 tablespoons of oil and add in the beef, garlic, and onion. Brown the beef on all sides and cook until the onions are tender. Transfer to the slow cooker.
Add the butternut squash, mushrooms, beef broth, thyme, salt & pepper, and barley to the slow cooker and cook on high for 4 hours or low for 8 hours. If soup gets too thick, add additional water or stock. Serve warm and enjoy!