Mix together the Shaoxing wine, soy sauces, brown sugar, olive oil, 5-spice, garlic pwoder and ginger in a medium bowl. Place the pork in the bowl and marinate for 15 minutes to up to 5 hours in the refrigerator.
Heat beef broth in a pot large enough to fit the pork. Add the onion, pork, and the marinade to the pot. Cover and simmer for 2-3 hours, until the pork is tender. Add water if necessary.
Remove the pork from the pot. Strain the braising liquid to remove any chunks. Then pour about 3 tablespoons of the liquid into a frying pan over medium high heat. Let it reduce slightly. Add the pork to the pan and cook for 2-3 minutes per side, until the sauce has caramelized slightly onto the pork. Remove pork from the pan and set aside.
Steam the buns according to the package instructions.
Fill each bun with shredded pork. Top with carrot, daikon, cucumber, and cilantro. Serve with hoisin sauce, if desired.