1/2 c. cider vinegar
1/2 c. water
1/3 c. apricot preserves or plum jam
2 T sugar
2 T soy sauce
1 T cornstarch
1/4 t. black pepper
1 to 1 1/2 lbs. pork tenderloin
1 T peanut or corn oil plus more if needed
Put the vinegar, water, apricot preserves or plum jam, sugar, soy sauce, cornstarch and black pepper into a small bowl and mix well. Set aside.
Trim any fat from the tenderloin and slice it into 12 pieces, each about 1 inch thick. Put these pieces between sheets of wax paper and pound them to 1/4-inch thickness with a rolling pin or the side of a can.
Put 1 T of the oil into a wok or large frying pan and begin heating over medium-high heat. Add half the pork medallions and cook about 2 min. per side or until they have lost their pink color. Remove from pan. Repeat until all are cooked.
Add the vinegar mixture to the wok or frying pan and bring to a boil. Return the pork medallions to the pan, and then reheat briefly. serve immediately.