Take one pork tenderloin, rinse, and place in roasting pan.
Slice as many onions as you want (I used about 3 jumbo, Vidalia onions), and saute slowly in oil until limp.
Next you will need: salt (I would recommend kosher salt or sea salt), pepper, and thyme.
Cover the tenderloin liberally in all of the above. Heat oil in another skillet and brown herb-covered pork briefly on all sides.
Cover the tenderloin with all those delicious-smelling, mouth-watering, steaming hot onions.
Insert a meat thermometer, and cook at 350 degrees until internal temperature reaches at least 145 degrees and juices run clear. Serve to hungry family.