In a large bag with a zip top, add 1 tablespoon soy sauce, 1 tablespoon sesame oil, garlic, pepper, and pork. Seal the bag pushing out excess air, turn to coat evenly, and refrigerate for at least 15 minutes but up to 24 hours.
Preheat grill to medium high.
Place a sheet of foil measuring about 18 x 24 inches on a flat surface, lightly spray with vegetable cooking spray.
Place potatoes in the middle of the foil, sprinkle with sesame seeds and all purpose seasoning, lightly spray with cooking spray. Fold sides in to cover the potatoes, seal top and sides creating a packet.
Place the pork and potato packets on the grill, cover and cook until pork is no longer pink in the center, about 12 minutes per side.
Remove only the pork from grill, place on a large cutting board and let sit for 5 minutes; slice into thin slices
Continue grilling potatoes until tender, about 10 more minutes. Carefully open packets to check potatoes, if not done reseal and continue grilling.
In a large bowl, whisk remaining 1 tablespoon soy sauce, 1 teaspoon sesame oil, and all of the remaining ingredients, except spinach.
Add spinach, potatoes, and pork to dressing and toss to mix well.