Marinade:

3 Cloves garlic, minced and mashed
2 tablespoons Dark rum
2 tablespoons Soy sauce
2 tablespoons Ginger, minced
3/8 cup Dark brown sugar
1/2 teaspoon Coarsely ground black pepper
2 Purple onions, sliced 1/4" thick
 

1.  Combine all marinade ingredients and place them in a glass or ceramic baking dish.
2. Clean off fat and other tissue from the pork by scraping along othe meat with the edge of a sharp knife.
3. Add pork to the dish with the marinade and turn it a few times coating it well with the seasonings.
4. Finally, place the onion slices around meat.
5. Cover with plastic not foil and keep in refrigerator for 4-6 hours.
6. Turn occasionally to season evenly.
7. Prepare charcoal and grill as usual.
8. When the coals are ready, remove pork from the marinade and place on the grill.
9. Also arrange the onion around the meat wherever space allows.
10. Reserve marinade liquid.
11. Turn meat and onions a couple of times until done. (For extra flavor, throw a small handful of hickory chips on the fire that have been soaked for 30 minutes in water).
12. When meat is done, place it in a warm place until ready to carve and serve.
13. Heat remaining marinade in a saute pan and glaze the grilled onions with it.
14. Slice the pork tenderloin into medallions, garnish with glazed onions and serve with ginger cream sauce.

*Ginger cream sauce recipe can be found in Avanti Savoia sauces.