Lightly pound the pork chops at least two times per side.
Marinade: In a medium bowl make the marinade by mixing together the orange juice, sugar, soy sauce, black soy sauce and salt. Add the pork chops and coat, let sit for 20 minutes.
Sauce: Mix orange juice, white vinegar, tomato sauce, sugar and cornflour together in a bowl. Set aside.
Cooking: Heat a large frying pan with 1 tablespoon oil over high heat. Fry the pork until both sides are brown; 3-5 minutes. Turn the heat to medium and continue to cook the pork chops until cooked through; 3-5 minutes.
Add the sauce and mix well. Turn off the heat and add the mandarins. Stir to mix.
Serve and garnish with orange zest.
Black soy sauce is darker, thicker and sweeter than ordinary soy sauce. You can find it in Asian supermarkets.