Preheat your oven to 400°F and line a baking sheet with parchment paper.
In a small mixing bowl, whisk together the honey, tamari, sesame oil, tomato paste, minced garlic, grated ginger, and five-spice powder to create the glaze.
Season the pork tenderloin with sea salt and black pepper, then brush half of the honey-garlic glaze over the meat.
Place the pork on the prepared baking sheet and roast for 20 to 25 minutes, or until the internal temperature reaches 145°F.
Halfway through the roasting time, brush the remaining glaze over the pork to build a thick, sticky crust.
While the pork is roasting, steam the baby bok choy for 3 to 5 minutes until the leaves are wilted and the stems are tender-crisp.
Remove the pork from the oven and let it rest for 5 minutes before slicing into thin medallions.
Serve the sliced char siu pork over the warm cooked brown rice with the steamed bok choy on the side.