Cut pork crosswise into 1/8-inch thick slices. Cut slices into 2-inch piwces.
REmove hard center sections from cabbage leaves, if necessary. Cut cabbage into 1-inch squares.
Mix soy sauce, ginger juice, sake, and sugar in a small bowl, stirring until sugar dissolves.
Heat 1 tablespoons oil in a 10-inch skillet over high heat. Add pork and saute, stirring constantly, until pork is half cooked, about 3 minutes. Remove pork from pan and reserve.
Add remaining 1 tbsp oil to skillet. Add cabbage and saute, stirring constantly, until almost tender, 1 to 2 minutes. Return pork to skillet; add soy sauce mixtre. Cook, stirring occasionally, until pork has finished cooking, 2 to 3 minutees. Serve immediately.