To make the Orange Balsamic Glaze

1. In a small sauce pan, heat orange juice, vinegar, salt and the black pepper. Note: this glaze is very strong and peppery if you use 3 teaspoons of pepper, so go by your preference. Bring to a boil and put on a fast simmer for about 20 minutes or until the sauce has been reduced by half. Pour through a fine sieve to filter out the pepper granules and set aside.

To make the Skewers

1. If using wooden skewers, soak six 12-inch skewers in water for an hour.
2. Cut the tenderloin into 24 one-inch cubes
3. Core the apples then cut in half then each half in half. Turn each piece and cut in half the opposite way to yield 8 chunks each instead of 8 slices each, total 24 chunks.
4. In a medium bowl, combine pork cubes, apple chunks, olive oil, salt and pepper. Mix to coat.
5. Thread the pork and apples onto the skewers (I put 4 of each onto each skewer) and grill over a medium hot grill for 5-8 minutes turning often. You want the pork to be pink but not raw and the apples to still have a bit of crunch. If you insert a probe thermometer into a piece of pork, it should read 140 degrees F.
6. During the last minute of cooking, brush with the glaze but be careful not to burn.
7. To serve, brush the skewers with extra glaze and serve.