Pat the pork butt roast dry with paper towels. Season both sides with salt and pepper.
Place 2-3 tablespoon of cooking oil into the bottom of a large frying pan and heat over medium-high heat.
Place the roast into the heated oil and brown on both sides.
Place into the Instant Pot, then place the onions and mushrooms on top.
Whisk together the mushroom broth and gravy mixes until smooth. Pour over the roast. Lift the roast slightly with a fork so that some liquid goes under the roast, this helps prevent it from sticking.
Seal the Instant Pot then press the meat/stew button, cooking for 120 minutes.
Let the Instant Pot release naturally.
To make the mushroom gravy, transfer the roast to a serving platter and cover with foil to keep hot.
Whisk together the slurry ingredients. Press the Saute button on the Instant Pot. Slowly whisk the cornstarch slurry into the mushroom mixture in the bottom of the Instant Pot until it's thickened. You may not have to use all of the mixture, just add enough to bring it to the desired consistency.
Shred the roast with two forks, pulling apart the meat and serve with the gravy and mushrooms on top.
Nutrition is an automatic estimate and will vary with the brands you use.
Recipe from https://fastandslowcooking.com/mushroom-gravy-instant-pot-pork-butt/