Start by heating the olive oil in your Instant Pot using the sauté setting. Once hot, add the chuck roast cubes in batches to avoid overcrowding. Sear them until they're browned on all sides; this step is essential for building flavor. After browning, remove the roast from the pot and set it aside.
Next, pour in the pepperoncini juice and beef broth. Use a spatula to scrape up the delicious browned bits stuck to the bottom of the pot. This is where a lot of flavor resides, and you don’t want to lose that!
Return the browned beef to the pot. Then, sprinkle the ranch seasoning and onion soup mix over the top. Toss in the pepperoncini, giving everything a gentle stir to ensure the meat is well coated in the flavorful liquid.
Arrange the slices of butter over the meat. This not only adds flavor but also contributes to a rich sauce.
Secure the lid of the Instant Pot and turn the valve from VENT to SEAL. Set it to cook on high pressure for 60 minutes. Once it’s done, let the pressure release naturally for 15 minutes before performing a quick release for any remaining pressure.
Carefully transfer the beef to a bowl and shred it using two forks. You’ll be amazed at how easily the meat falls apart; this is a sign that it’s cooked perfectly!
While you’re shredding, return the liquid in the pot to sauté mode and let it come to a bubble. This will help to intensify the flavors.
In a small bowl, whisk together the cornstarch and water until smooth. Stir this mixture into the bubbling sauce in the pot. Keep stirring until it thickens to your desired consistency.
Finally, add the shredded meat back into the pot, stirring well to coat it in the rich sauce. You want every bite to be loaded with flavor!