Whisk the hoisin, soy sauce, 1 tablespoon of the honey, shaoxing wine, five spice, garlic, and white pepper together. Set 2 tablespoons of the marinade aside in the fridge for glazing later.
Coat the tenderloins in the rest of the marinade in a zip bag or container. Marinate at least 1 hour, ideally overnight. The flavor genuinely improves with time, so plan ahead if you can.
Heat the oven to 220C (425F). Set a rack over a foil-lined tray and pour a cup of water into the tray. The drippings from char siu marinade burn and smoke without it.
Roast the tenderloins on the rack for 15 minutes.
Stir the remaining 1 tablespoon honey into the reserved marinade. Brush the pork all over with it, then roast another 8 to 10 minutes until the internal temperature reads 60 to 62C (140 to 144F) at the thickest point.
Optional but worth it: run the pork under the broiler for 1 to 2 minutes for charred, lacquered edges. Watch it the entire time, honey goes from caramel to carbon fast.
Rest 10 minutes before slicing. The temperature carries to about 65C (149F) and the juices stay in the meat instead of on the board.