To marinate and grill the peaches
Place the peach halves, cut side up in a shallow dish, sprinkle with pepper and spoon the balsamic vinegar over them making sure the pit spaces are filled.
Marinate for 15 minutes before turning the peaches over and marinating for an additional 15 minutes.
Cook for just a few minutes on a lightly oiled grill.
Dice the peaches and keep warm until the pork is ready.
If you like you can toss the diced grilled peaches with a teaspoon or two of honey and some fresh thyme leaves before serving.
For the pork tenderloin
Mix together all the spices, salt, pepper and garlic powder.
Rub over the entire surface of the pork tenderloin and let it sit in the fridge while the peaches marinate.
Grill over medium high heat, turning to cook on all sides, until the internal temperature of the tenderloin reaches 150 - 160 degrees on a meat thermometer.
Allow the cooked tenderloin to rest at room temperature for 10 minutes before slicing and serving with the grilled peaches.