I made a HK style roast pork belly few days ago, which was very delicious and the pigskin was so crispy!
The roast pork was not difficult to make it, only you had to pay attention to the time.

Basically I followed the receipt from here:
脆皮燒肉【自家烤製】 Crispy Roast Pork Belly

And she's right, after cooking this roast pork, we definitely have to clear the oven!