Prepare the pork and marinade. Mix all ingredients in a small bowl and pour over the pork tenderloin in a ziploc bag or dish. Let marinade for 30 minutes in the fridge.
Prepare the coleslaw. Meanwhile, mix mayo, olive oil, seasonings, apple cider vinegar, and honey together in a small bowl. Pour over the coleslaw mix in a large mixing bowl. Toss well to coat coleslaw and season to taste. Store in an airtight container in the refrigerator until ready to serve.
Cook pork. Heat a cast iron grill over medium and coat with cooking spray. Once hot, add the pork tenderloin to the grill and sear. Discard excess marinade. Set a timer for 15 minutes and cover loosely with a lid. Every few minutes, using tongs, flip the tenderloin on all sides to cook. At the 15-minute mark, check the internal temperature. It’s done when it reads 145f degrees.
Remove tenderloin and let it rest for 5 minutes on a cutting board. Slice into rounds and serve alongside coleslaw. Optionally drizzle a little more balsamic vinegar over the pork.
Make it AIP: Omit black pepper and dress coleslaw in olive oil and vinegar without mayo.