Prep your pork tenderloin by trimming off the outer layer of connective tissue.
Whisk together the marinade: oil, coconut aminos, vinegar, mustard, garlic, onion powder, black pepper. Place the pork tenderloin and marinade in a large container. Marinade for 4-24 hours.
When ready to grill, prepare your charcoal or gas grill. Set up both indirect and direct heat. For the charcoal grill, pile the charcoal on one side of the grill and light. For the gas, heat up one burner to medium high heat, and another to low heat (or no heat).
Once grill is ready, place the tenderloin over the direct heat. Cook for 2-3 minutes per side, then move to the indirect heat and cover the grill. Turn occasionally, and baste with remaining marinade. Once the internal temperature reaches 145 degrees F, remove from the grill and let rest for 7-10 minutes.
Slice into medallions and serve!