Pat pork chops dry with paper towels. Season each side with a sprinkling of pepper, and salt if desired. Heat oil in a large nonstick frying pan or skillet over medium-high heat until just hot then add pork chops and brown both sides (around 5 minutes if your pork chops are around 1/2-inch thick).
Stir cider and brown sugar together and add to the frying pan. Reduce heat to low and simmer the pork chops, uncovered, turning the chops after a minute, until the meat is almost cooked through but not quite (about 2 minutes). Remove pork chops to a plate with a fork.
Add the vinegar and ground mustard to the frying pan juices and bring to a boil, scraping up any brown bits on the bottom of the pan with a spatula. Continue to cook until the glaze mixture is reduced to about 1/3 cup. It will take 5 to 10 minutes. The cider mixture will get bubbly when it is just about at the syrup/glaze stage.
Turn off heat. Place the pork chops back in the frying pan along with any juices that formed on the bottom of the plate.
Flip chops over to coat both sides with the cider glaze, cover frying pan and let sit for a minute or two to blend flavors. Check thickest part of the pork chop for desired doneness and serve.