First, turn the Instant Pot to “Saute,” and add the oil. Season both sides of the pork chops with salt and pepper. Then add them to the pot, and cook about 3-4 minutes on each side until lightly browned. If the pork chops are large, work in batches of two.
Next, remove the pork chops from the pot, and set aside. Keep the Instant Pot on saute, and add the mushrooms and onions. Stir to combine, and cook until the mushrooms begin to soften and the onions start to become translucent. This usually takes about 5-7 minutes.
Then, add the garlic, and cook an additional 30 seconds. Turn off the saute function, then add the chicken broth. Place the pork chops back into the Instant Pot, and close the lid. Set the valve to “Sealing,” and use the manual/pressure cook option to cook the chops on high pressure for 10 minutes.
After the 10 minute pressure cook has finished, allow an additional 10 minute natural release before opening the valve. Remove the pork chops, and set aside.
Now, combine the cornstarch and half and half in a small bowl. Turn the Instant Pot back to “Saute,” and add the cornstarch mixture. Stir until the gravy begins to thicken then turn the pot off. Add the sour cream and stir to combine.
Last, serve the gravy over the pork chops while hot. Any leftovers should be stored in the refrigerator for up 3 days.