In a large bowl, combine 1 cup (240 ml) of the soy sauce with the sugar, garlic, and scallions, stirring until mixed.
Score the skin of the pork by slicing a crosshatch pattern through the skin down to the meat. This will help excess fat render out and allow more of the marinade to soak in.
Place the pork in the marinade and toss to coat evenly. Marinate for one hour.
Preheat the oven to 275ºF (140°C).
On a baking sheet, place the asparagus halves to the right and diced potatoes to the left. Toss the vegetables with the oil, salt, and pepper. Place the marinated pork in the middle of the baking sheet.
Bake 1 to 1 ½ hours, depending on the weight of the pork.
Raise the heat of the oven to 500ºF (260ºC).
In a small bowl, combine the brown sugar, honey, and remaining soy sauce, stirring until smooth.
Spoon the honey glaze over the top of the pork, making sure to fill the cracks and crevices on top.
Bake for 20 minutes until sugar is dark brown and caramelized, and the top of the pork is crispy.
Remove the vegetables and pork from the tray, making sure to save all the juices.
Slice the pork into ½-inch (2 ½ cm) slices, and plate with the roasted vegetables. Spoon the reserved pan juices on top of the pork.