Pour all marinade ingredients, except 1 ½ tablespoons honey, into a saucepan and stir together. Simmer over medium-low heat for about 20 minutes. Remove from heat and cool to room temperature.
Lightly season pork tenderloin with salt and white pepper.
Place pork tenderloin in a re-sealable plastic bag and pour marinade over pork, reserving ¼ cup of the marinade.
Shake bag around to ensure all of the pork is covered in marinade.
Remove as much air from the bag as possible, seal and refrigerate for at least 4 hours and up to 24 hours.
Preheat oven to 350˚F.
Remove pork from bag with marinade and place onto a baking sheet with a rack inserted in it (or a roasting pan).
Pour marinade into a mixing bowl and stir in remaining 1 ½ tablespoons honey.
Roast pork for 30 to 40 minutes (or until the internal temperature reaches 145 F. [with a light pink center] and160 degrees F.), generously basting with the used marinade, every 10 minutes.
Once pork has reached the correct internal temperature, glaze pork once more and broil on high for 1 to 2 minutes or until pork is glossy and crisp. Remove from heat and allow loin to rest for 3 to 5 minutes.
Slice into ½ inch slices, top with sliced green onion and serve over rice with reserved char siu sauce on the side.