In a small bowl, whisk together the honey, hoisin sauce, tamari, toasted sesame oil, grated fresh ginger, minced garlic, and Chinese five-spice powder to create the marinade.
Place the pork tenderloin in a shallow dish or resealable bag and pour two-thirds of the marinade over it, reserving the rest for basting.
Let the pork marinate in the refrigerator for at least 30 minutes to allow the flavors to penetrate the meat.
Preheat your oven to 400°F (200°C) and heat the avocado oil in a large oven-safe skillet over medium-high heat.
Sear the pork tenderloin on all sides until golden brown, about 2-3 minutes per side.
Transfer the skillet to the oven and roast for 12-15 minutes, or until the internal temperature reaches 145°F, basting with the reserved marinade halfway through.
While the pork rests for 5 minutes, steam the baby bok choy until the stalks are tender but still have a slight crunch.
Slice the pork into medallions and serve immediately alongside the bok choy, garnished with a sprinkle of sesame seeds.