Place the ground pork in a large bowl. Add 3 tablespoons of the teriyaki sauce, the grated ginger, panko breadcrumbs, egg, most of the sliced green onions, minced garlic, and sesame oil.
Mix everything with your hands until the ingredients are evenly combined but not overworked.
Shape the mixture into a loaf about 8 inches long and place it on a parchment-lined baking sheet.
Brush the top with the remaining teriyaki sauce.
To freeze, cover the loaf tightly with plastic wrap and foil, then place the sheet in the freezer until the meatloaf is solid. Transfer to a freezer bag for longer storage.
When ready to cook, thaw overnight in the refrigerator. Bake at 375°F for 45 to 55 minutes until the internal temperature reaches 160°F. Sprinkle with sesame seeds and the remaining green onions before serving.