Whisk together soy sauce, 3 tablespoons oil, the ginger, sugar, chopped scallion, and ½ teaspoon pepper.
Arrange pork chops in a 9-by-13-inch nonreactive baking dish. Reserve 3 tablespoons marinade, and pour remainder over pork chops. Marinate, covered with plastic wrap, flipping chops halfway through, for 45 minutes.
Heat remaining tablespoon oil in large skillet over medium-high heat. Remove pork chops from marinade, and sear for 3 ½ to 4 minutes. Reduce heat to medium. Flip chops, and sear until just cooked through, 3 ½ to 4 minutes more. Transfer chops to a board or platter. Let rest for 5 minutes.
Add reserved 3 tablespoons marinade to skillet. Simmer over medium heat until thickened, about 30 seconds. Spoon sauce over chops. Garnish with thinly sliced scallion.
