Place pork in a large, sturdy zip-loc bag. In a small bowl or measuring cup, whisk together the garlic, apple cider vinegar, mustard, maple syrup, olive oil, salt, and pepper. Seal the bag tightly, then “squish” the bag so that the pork is coated on all sides. Place in the refrigerator to marinate for 2 hours or 1 day, turning occasionally. Let stand at room temperature 30 minutes prior to grilling.
Assemble the vegetable packets: Tear off four, 12-inch squares of aluminum foil and arrange in an assembly line. Place the broccoli, tomatoes, and zucchini in a large bowl, drizzle with olive oil, then sprinkle with garlic powder, salt, and pepper. Toss to coat. Spoon 1/4 of the mixture into the center of each foil square, then seal the squares by pulling opposite sides of each square up so that they touch, then folding them over and over each other so that you create a packet. Fold the ends of the foil inward to seal the pouch.
When ready to cook, preheat the grill to medium (about 350 degrees F). Brush the grill with oil. Remove the pork from the marinade, shake off excess. Discard the marinade and bag. Cover and cook, turning once every two minutes, until the internal temperature reaches 140 degrees F, 12 to 15 minutes. Remove the tenderloin to a plate, cover, and let rest for 10 minutes before slicing.
Just before removing the pork from the grill, add the vegetable packets to the grill, also over medium heat. Cover the grill and let the packets cook for 10 minutes, until the broccoli is crisp tender. While the vegetables are still hot, sprinkle with cheddar cheese. Serve hot with sliced pork.