Toss tenderloin with 1 tablespoon soy sauce in medium bowl; set aside. Whisk together Knorr® Roasted Chicken gravy mix and water in small bowl; set aside.
Heat 1 tablespoon oil in large nonstick skillet over medium-high heat. Coat tenderloin in cornstarch and cook in batches until done. Remove tenderloin and set aside.
Heat remaining 1 tablespoon oil in same skillet over medium-high heat and cook onion and pepper, stirring occasionally, until crisp-tender, about 3 minutes. Stir in ginger and cook 30 seconds. Stir in pineapple juice, remaining 1 tablespoon soy sauce and gravy mixture and bring to a boil over medium-high heat, stirring occasionally.
Add tenderloin and pineapple to skillet; reduce heat to medium-low and cook, stirring frequently, until sauce is thickened and pork and pineapple are heated through, about 5 minutes. Serve, if desired, over rice.