Combine all of the char siu sauce ingredients in a sauce pan, heat and stir until blended and becomes slightly thickened and sticky.
Cut pork into about 6 to 8 large peices. Use 2/3 of the sauce to marinade the pork. Add the chopped garlic to the pork, ensure the meat is well covered in marinade and refrigerate overnight.
Put remaining marinade in the fridge in a separate container.
Next day, heat the oven to 160 degree.
Put the pork into an oven bag and cook for 20 minutes.
Check to see if the pork is cooked by slicing the meat.
When the meat is just cooked, remove from the oven bag and drain any juices.
Heat a wok or frying pan with sesame oil and add the cooked pork.
Pour the remaining marinade over the pork and continue to turn until the pork is well coated and the sauce is lovely and sticky.