In a food processor, combine the Italian seasoning, fresh curly parsley, dried rosemary, sage leaves, fennel seeds, garlic cloves, kosher salt and black pepper and process until smooth.
Place the pork on top of a cutting board and spread the herb mixture all over the pork, put the twine under the pork and tie around, wrap it in foil and let it rest in the fridge for at least 4 hours.
Select SAUTE-High, set the time for 30 minutes and press START.
Add the olive oil to the inner pot. When oil is hot, add in the pork and sear of each side until browned. Take out the pork and set it aside.
Press CANCEL to turn off sauté.
Pour in chicken stock to deglaze the pot. Stir well to remove any brown bits on the bottom. Ensure there is nothing stuck to the bottom of the pot.
Put the pork back into the inner pot, and place the onions, celery, and mushrooms around and on top.
Close the Pressure Cooking Lid on the pot and set to VENT.
Select SLOW COOK-Custom-Low for 8 hours.
When done, carefully open the Pressure cooking Lid. Remove the pork from the inner pot, remove butchers’ twine, and shred it.
Spread shredded meat and some of the juices on a baking sheet lined with foil and broil until the meat gets browned. Mix the meat up and repeat until most of it is browned.
Serve in a sandwich with provolone cheese if desired and enjoy!