I found this recipe on another site, it had great ratings so I made it. It was the best we have ever had! We had two couples over for dinner and everyone loved it and ate every last piece! Absolutely delicious!
Place soy sauce, brown sugar, sherry, dried onion, cinnamon, olive oil, and a touch of garlic powder in a large resealable plastic bag. Seal, and shake to mix. Place pork in bag with marinade, seal, and refrigerate for 6 to 12 hours.
Preheat grill for high heat.
Lightly oil grate. Place tenderloins on grill, and discard marinade. Cook 20 minutes, or to desired doneness. Slice into medallions, and serve.