This restaurant offers the best breakfast in Sai Kung, they even do poached eggs.
They also have black pudding. However they do not do breakfast anymore.
Source:
https://www.openrice.com/zh/hongkong/review/the-best-breakfast-in-sai-kung-e96527
Xtreme:
西貢普通道路 72 號
72 Po Tung Road, Sai Kung