Set your Instant Pot to the sauté function. Add the olive oil. Once hot, sauté the diced onion and minced garlic for 2–3 minutes, until the onion is translucent.
Add the beef tips and sear for about 1 minute to develop flavor. (This step creates the Maillard reaction — the browning that gives you that deep, rich taste!)
Stir in the beef broth, red wine, Worcestershire sauce, sliced mushrooms, Italian seasoning, salt, and black pepper. Close the lid and set the vent to sealed. Set to pressure cook on high for 35 minutes.
Allow a 10-minute natural release, then carefully turn the valve to vent to release any remaining steam (quick release).
Set the pot back to the sauté setting. In a small bowl, make a corn starch slurry by whisking together the cornstarch and ¼ cup cold water until smooth.
Once the liquid is gently boiling, stir in the slurry and cook for 2–3 minutes, stirring, until the gravy thickens to your liking.
Serve hot over white rice, egg noodles, or your favorite side dishes!