Coat the pork neck in the marinade ingredients and vacuum pack with the marinade. Sous-vide the pork at 63°C/145° F for 12-16 hours. (See note below.)
Remove from the vacuum bag and glaze with hoisin, honey, and golden syrup.
Roast at 215°C/420°F for twenty minutes until crisped.
Don’t have a sous-vide immersion circulator? Combine the pork with the marinade ingredients and let sit for 12-48 hours in the refrigerator. Roast, covered in foil, or in a baking bag, at 190°C/375°F, for 1 hour. Uncover, raise the heat to 215°C, glaze and continue roasting for twenty minutes until bubbling and charred in spots.
Note: Sous-vide is a method of cooking that involves putting the ingredients in a vacuum sealed pouch and immersing it in a carefully temperature controlled water bath. When you cook sous-vide, you should always wear gloves with sous vide or outside bacteria will grow at the low temperatures and cause the food to spoil.
Note: The charsiu recipe makes double the amount needed for the bao. However, charsiu will always be devoured. Eat it plain, in fried rice or garnish it on your greens.