Keep the serving plates in the oven at the lowest setting so they are warm when you serve.
Place the pork chops in a resealable plastic bag. Finely chop the garlic and mince the ginger then put them in a small bowl. Add the brown sugar, vinegar, soy sauce, and mirin (or Sherry) then stir until the brown sugar is dissolved. Pour the mixture into the bag, then seal it and turn it to coat the pork chops with the marinade. Let stand 30 min at room temperature or chill in the refrigerator 3 h to overnight.
Pour out the marinade from the bag into a small saucepan, bring to a boil, then simmer 2 min. Set aside.
Meanwhile, heat the oil in a skillet over moderate heat until hot but not smoking. Add the pork chops thensauté until just cooked through, 3-4 min per side, depending on the thickness. Serve on the warmed plates. Drizzle the chops with the hot marinade.