Preheat oven to 350 degrees.
Arrange sliced onions, apples and seasonings in an oven proof dish.
Pour wine or water over the mixture.
Heat oil in a large fry pan. Brown the pork tenderloins on all sides.
Arrange the tenderloins on the apple mixture.
Spoon some apple mixture over the tenderloins.
Bake for about 20-25 minutes until cooked through.
Remove from the oven and let rest for about 10 minutes before slicing.
Serve slices of pork with the apple mixture.