Put half the oil in a heavy skillet or wok and turn heat to high. When hot, add pork and cook, stirring once or twice, until browned; don’t worry about cooking it through. Remove with a slotted spoon.
Add remaining oil, followed a moment later by squash. Cook, stirring occasionally, for about 2 minutes. Add ginger and scallions and stir; add stock and cook until it reduces by about half. Add soy sauce and cook 30 seconds or so.
Return pork to skillet and cook about 1 minute, stirring. There should still be liquid remaining in pan. Garnish and serve.