2 teaspoons vegetable oil
1 large onion, thinly sliced
3 slices fresh celery
1 pound pork tenderloin meat, cut into 1/4 inch slices
1 cup packed brown sugar
10 tablespoons balsamic vinegar
Heat the oil in a large skillet over medium heat. Stir in green onions and celery and saute for 2 to 3 minutes. Cook until celery is brown. Reduce heat and cook, stirring occasionally, for 10 minutes longer.
With a flat spoon cut thick slices of celery on each side or on all 4 sides of the pork loin. Transfer the slices to meat platter. Divide the warm brown sugar between the sides of the pork loin and spread over the celery slices. Slice open the rib ends, bearing in mind that opening is the one to seal the lids, and mark on the meat with a fork. Reserve 1/2 cup of the brown sugar for dipping and serving. Slice open the valve of a pint glass around the edge. Pour vinegar into a flask and stir in enough to coat pork. Add remaining brown sugar to the sauce, concentrating the pork and basting lightly. Transfer sauce to a serving dish and serve with some of the treated celery slices carefully submerged in marinade.