Slice pork tenderloin lengthwise, spread open and pound just enough to flatten it out a little. Season.
Preheat skillet, add oil, saute onion and garlic over medium heat eight minutes, stirring frequently. Add a few drops of honey at the eight minute mark. This will darken and caramelize the onions. Add capers and raisins and cook two more minutes. remove from pan, clean pan and heat again. Add a little oil or spray. Brown meat on each side. Place in baking dish. Put onion mixture on top of meat. Add grape juice. Bake 30-40 minutes. Cool for five minutes before slicing.