Set your Instant Pot to "Sauté" mode and heat the olive oil. Season beef cubes with salt and pepper, then brown them in batches, about 2-3 minutes per side. Remove and set aside.
Add the onion to the pot and sauté for 3 minutes until softened. Add garlic and cook for another minute until fragrant.
Stir in the tomato paste and cook for 1 minute, then pour in the beef broth and Worcestershire sauce. Scrape up any browned bits from the bottom of the pot.
Return the beef to the pot and add the carrots, potatoes, celery, bay leaves, and thyme. Stir to combine.
Close the lid, set the valve to "Sealing," and cook on high pressure for 35 minutes.
When done, allow a 10-minute natural release, then carefully quick-release any remaining pressure.
If you'd like a thicker stew, set to "Sauté" mode again and stir in the cornstarch mixture. Cook for 2-3 minutes until thickened. Remove bay leaves before serving.