Press “SAUTE” on the Instant Pot and heat up the vegetable oil.
Add meat to the hot oil and cook for 5 minutes.
Flip it over and continue to cook for 5 more minutes. Add more oil, if needed.
Remove meat from the Instant Pot and set aside.
Slowly add beef broth to the IP; stir to loosen up all the browned bits from the bottom of the pot.
Whisk in pepperoncini juice.
Transfer meat back into the IP.
Sprinkle ranch seasoning mix and the gravy mix over the meat.
Add pepperoncinis and butter.
Turn off the saute mode.
Close IP with the lid and set the steam release knob to Sealing position.
Press the Manual button (or pressure cook button) and set to 60 minutes HIGH PRESSURE.
When the cooking cycle ends, do a Natural Pressure Release for 15 minutes.
Turn off the pot and release remaining pressure by turning knob to the venting position.
When the pin drops, open the lid.
Remove pot roast from the IP; let rest 10 minutes before cutting.
Serve pot roast with juices. See recipe notes below*