Make the marinade by combining the marinade ingredients in a bowl — from the 1/3 cup soy sauce through the five spice blend.
Rinse and pat dry the pork tenderloin. Add the pork to a large sealable plastic bag. Pour in the marinade and close the bag. Gently toss the pork to get it well coated in the marinade. Put in the refrigerator to marinate for 1 to 2 hours.
Remove the pork from the refrigerator 15 minutes prior to the time you plan to start grilling. Preheat a grill to medium high and light coat the grill with oil spray.
When the grill is hot, remove the pork from the marinade, gently shaking the excess marinade back into the bag.
Place the pork tenderloin on the grill, and grill covered for a total of 16 to 20 minutes, turning halfway through the grilling time.
Pour the excess marinade from the bag into a small sauce pan, and add the remaining sauce ingredients–white wine, 1 tablespoon soy sauce and orange juice. Bring to a boil, then reduce to a gentle boil for 10 minutes, stirring occasionally. Keep warm as the pork finishes cooking.
Check the pork for doneness at 15 minutes of grilling time. Pork tenderloin should be 145 degrees internal temperature and still juicy and moist when done.
When the pork is done, let it rest on a platter for 5 minutes. Slice the pork and plate, drizzling a bit of the sauce over the pork and passing extra sauce at the table. Enjoy!