Trim pork tenderloin according to instructions in post above.
In a large ziploc freezer bag or container, whisk together apple juice, maple syrup, canola oil, cider vinegar, salt, garlic, ginger, mustard, pepper and pepper flakes. Reserve ½ cup of marinade for basting later.
Add tenderloin, seal tightly, and turn to coat.
Refrigerate for 2-24 hours.
Preheat grill to medium-high heat (roughly 400°F). Remove tenderloin from marinade and discard the bag.
Grill pork tenderloin for 8-12 minutes per side (exact cook time will depend on exact grill temperature and width of tenderloin), basting with reserved marinade several times during the cooking process.
When the tenderloin reaches an internal temperature of 140°F, remove from the grill and let rest for 5-10 minutes before slicing.
