1. Heat oil to medium-high in large heavy skillet. Carefully add pork chops (do not overcrowd pan, cook in two batches if necessary)and slowly brown both sides. Drain fat.
2. In bowl, mix together thoroughly 1/2 cup of the water, teriyaki sauce, ketchup (or tomato sauce) and brown sugar then pour over pork chops in skillet.
3. Cover and simmer slowly for 30 minutes, turn over and simmer about 20 - 30 minutes or until chops are cooked thoroughly. Remove chops from pan, cover and set aside (keep chops warm).
4. In small bowl, combine corn starch with 1/4 cup COLD water then pour into skillet and stir, loosening up the drippings left in skillet. Continue cooking, stirring constantly, until mixture boils. Reduce heat to low.
5. Put chops back in pan, simmer together about 2 - 3 minutes just to be sure all the chops are coated with sauce and nice and hot.