Hit SAUTE button on Instant Pot, and when it reads HOT, add the olive oil, and carefully tilt pot to ensure it coats bottom of pot evenly
Add 2 of the chuck roast pieces, and sear for about 2 minutes per side, then remove to a plate. Sear the last piece on both sides, and remove
Hit CANCEL to turn pot off, then add some of the beef broth and deglaze pot with wooden spoon or spatula
Place chuck roast back in pot, and add minced onions, salt, pepper, butter, pepperoncini peppers and juice
Add remaining beef broth, cover, turn vent to sealing position, and hit PRESSURE COOK for 60 minutes
Allow natural release for 20 minutes, then hit CANCEL, do a quick release, then open lid when pin drops
Stir in ranch dressing, transfer roast to serving platter and top with peppers some of the gravy, if desired