Season the beef chunks with salt and pepper to taste. Heat the Pressure cooker* to Sauté Mode and add the olive oil, enough to coat the bottom of the pot. Once hot, add the beef in an even layer (you may have to do this in batches). Let the beef cook until it forms a golden brown crust on all sides. Remove from pot to a bowl and set aside.
Add the onions and garlic to the pot and cook, until fragrant about 3 minutes. Stir in the beef broth and use a wooden spoon to gently scrape any stuck on bits from the bottom of the pot.
Add in the tomato paste, Worcestershire sauce, potatoes, carrots, celery and beef (along with any collected juices from the bottom of the bowl). Place the thyme and bay leaf on top (do not stir) and close lid.
Set pressure cooker to HIGH pressure for 35 minutes (make sure the valve is set to the sealed position). After the 35 minutes is up, let the pressure cooker naturally release pressure for 15 minutes, then flip the valve and release any remaining pressure.
Remove the thyme leaves (if using fresh) and bay leaf and discard. Turn the pressure cooker to Sauté Mode. In a small bowl whisk together the cornstarch and water, creating a slurry. Pour into the beef stew and stir until the mixture begins to thicken.
Turn off heat and stir in the frozen peas until they're heated through and enjoy!
*Recipe can be made in an 8 quart or 6 quart instant pot or pressure cooker.