Season beef with salt, pepper, and garlic powder on all sides.
Press the SAUTE button the Instant Pot and let it heat up. Once it’s hot, add olive oil to pot.
Add half of the beef tips to the hot pot and saute for about 1 minute (just to sear the outside). Flip over and saute for one more minute. Remove beef tips from Instant Pot.
Repeat with other half of beef tips, adding more olive oil if needed.
Dump all beef tips back into Instant Pot and place onions and mushrooms on top. Stir and scrape the bottom of the pot, loosening up all the browned bits so that you don’t get the “BURN” message on your pot (and getting maximum flavor in your dish!).
In a mixing bowl, mix together beef broth, Worcestershire sauce, ketchup, red wine vinegar and Italian seasoning. Pour on top of beef tips, onion, and mushrooms.
Place the lid on top of the Instant Pot and move the valve to SEALING. Press the MANUAL (PRESSURE COOK) button and set timer for 30 minutes.
When the timer is done, let the pressure do a NATURAL RELEASE (it will take at least 20 minutes, but I even prefer to let the beef sit in there for a couple hours to make sure it is super tender).
Remove the lid and press the SAUTE button.
In a separate small bowl, mix cornstarch together with water in a separate bowl. Pour cornstarch mixture into Instant Pot and mix well. Cook on SAUTE for a few minutes or until the liquid starts to thicken and turns into a gravy.
Serve over mashed potatoes, rice, or hot noodles.