Step 1: Arrange the chops in a nonreactive dish (i.e., glass, ceramic, or stainless steel) just large enough to hold them. Combine the soy sauce, oil, sugar, scallions, garlic, and ginger in a mixing bowl and whisk to mix. Pour this mixture over the chops and marinate for at least 2 hours and as long as 8 hours (the longer, the richer the flavor), turning the chops from time to time so they marinate evenly. Alternatively, marinate the chops in a resealable plastic bag.
Step 2: Set up your grill for direct grilling and preheat to high. Brush and oil the grill grate. Using tongs, remove the chops from the marinade and hold them over the pan to drain well. Do not discard the marinade. Arrange the chops on the grate and grill for 2 minutes per side.
Step 3: Return the chops to the marinade, turning to coat both sides. Let marinate for 3 minutes. Drain well. At this point you can boil the marinade until reduced by one-third and spoon it over the cooked chops as a sauce.
Step 4: Continue grilling the chops until darkly browned on both sides and cooked through. Transfer the chops to a platter or plates. Spoon a little sauce, if using, on top and sprinkle with the reserved scallion greens.