Set the electric pressure cooker to saute and heat until “hot.” Add one tablespoon butter and the onions. Cook until softened. Push to the side or remove and keep warm.
Add additional butter if needed. Salt and pepper the pork on both sides. Begin searing the pork chops in small batches to brown on each side. Set aside the browned pork chops and keep warm as you cook all of the pork chops. Add butter as needed to lubricate the pressure cooker liner. (To save time, you could also be browning pork chops in a large skillet over medium-high heat.)
Deglaze the liner with broth, scraping the bottom with a wooden spoon to remove any cooked on pieces.
In the pressure cooker liner, layer the onions and then pork chops allowing the pork chops to overlap slightly. Create additional layers as needed.
Cover and set to “pressure cook” or “manual” for 8 minutes. Allow the pressure cooker to naturally release the steam for at least 5 minutes before quick release.
Remove the pork chops from the pressure cooker. Cover and keep warm.
Change the pressure cooker setting to saute and bring the broth to a boil. Stir in xanthan gum until thickened slightly. Turn off the electric pressure cooker and then stir in the sour cream.
Serve pork chops with sauce.