Place garlic, onions and chili into a cast iron casserole dish with lid. Drizzle with a little bit of oil.
Place pork on top, and sprinkle with sugar. Add fish sauce, tomato paste, vinegar and tomatoes and cover. Bake in 150°C oven for 4 hours. Pork will be very tender.
Stir occasionally through out cooking time to combine all ingredients.
Add BBQ sauce and ‘pull’ the pork with a fork to stir sauce through. It will shred easily if cooked long enough. Tear a few coriander leaves and stir through.
Taste and adjust seasoning if needed. (Salt and cracked pepper.)
Serve on buns, with coleslaw on the side.
Alternatively, if you have a slow cooker, you can use it, follow the recipe as written and cook on a high setting.