Whisk the apple cider vinegar, dijon mustard, brown sugar, olive oil, garlic powder, salt, onion powder, and pepper together in a medium bowl. Place this mixture into a large ziplock freezer bag.
⅓ cup apple cider vinegar, 2 Tablespoons dijon mustard, 2 Tablespoons brown sugar, 2 Tablespoons extra-virgin olive oil, 1 Tablespoon garlic powder, 1 teaspoon salt, 1 teaspoon onion powder, ½ teaspoon pepper
Trim any excess fat or silver skin off of the pork tenderloin then add it to the bag. Squish everything around so that the meat is coated.
2 pounds pork tenderloin
Place this in the fridge to marinate for at least an hour, but you could also make it up the night before. Squish the bag around once in a while to make sure the coating is even.
When you are ready to grill, brush the grill with some oil to prevent sticking. Remove the pork tenderloin from the marinade and discard any leftover marinade.
Avocado oil for brushing on grill
Heat the grill until the temperature inside is 500°F. Put the pork on the grill and use tongs to turn it slowly as each side sears. (This will only take a minute or 2 per side.)
Then reduce the heat to 350°F, close the lid, and continue cooking for another 12 minutes, turning if needed.
Check the temperature of the pork with a meat thermometer to be sure it is 145°F.
Let the meat rest before slicing.