Mix soy sauce, cornstarch, sugar, and ginger. Coat meat with soy sauce mixture. Heat 1 tablespoon oil in a large frypan. Add green pepper strips. Cook for 2 minutes, stirring constantly. Remove green pepper from pan.
Heat remaining 2 tablespoons oil. Add meat. Cook for 1 to 2 minutes, stirring constantly, until beef is lightly browned. Add green pepper and pineapple. Heat through. Serve over rice.
