Add the soy sauce, vinegar, sugar, ginger, sesame oil, garlic, and red pepper to a large Ziploc bag. Add the pork tenderloin. Seal and marinate in a refrigerator for 8 hours or overnight, turning the bag occasionally.

Preheat the oven to 425° F. Heat a large ovenproof skillet over medium-high heat. Remove pork from bag, reserving marinade. Add vegetable oil and pork to pan, cook 6 minutes, browning on all sides.

Place the pan in the oven, and bake for 15 minutes or until the meat thermometer registers 145° (medium) or until the desired degree of doneness. Remove from oven and let rest for 5 minutes before slicing.

While meat is resting, bring reserved marinade to a boil in a small saucepan. Reduce heat, and simmer for 5 minutes.

To serve, cut pork into ½ inch thick slices and drizzle with sauce.