Make sure your meat is completely thawed. Place pork in a tray and sprinkle with the Chinese five spice powder. Rub powder into meat, massaging as you go to make sure pork is well seasoned.
Preheat oven to 175° C, fan. Take a deep oven dish, glass or ceramic. Put chopped onion into dish and spread on the base. Add ginger, chili, garlic and mix. Lay pork on top of onion mixture.
Mix together in a jug, the orange juice, vinegar, soy sauce, honey, ketchup and sweet chili sauce. Season with freshly ground black pepper. Pour mixture over pork. Finally, pour over the chicken stock.
Cover meat with a piece of greaseproof paper with a small hole in the middle. It’s ok if the paper touches the meat. Cover the pan with heavy duty foil, then with the pan lid if it has one. If not, cover pan with double foil.
Transfer pan in the preheated oven. Bake for 2 hours. Then, lower the heat to 160° C and bake 2 hours more.
Remove meat from the oven. At this stage you can let it cool to room temperature and place in the fridge for 24 hours.
If you want to serve the same day, remove, foil and paper from pan and transfer pork to another platter (KEEP the sauce please!).
Shred pork with your hands or 2 forks. Mix shredded meat with 4-5 tablespoons of the pan juices. Cover and set aside.
To finish the sauce, transfer all the pan juices in a blender and blend until smooth. You can also use an immersion blender. Transfer sauce in a saucepan and bring to a simmer over medium heat. Simmer for 15-20 minutes until reduced and thickened slightly. Set aside until serving time.