Use a bamboo steamer or a folding steamer basket with enough room for each piece of fish to lie flat.

A ball-shaped dumpling with a whorl - like pattern on the top, stuffed with a variety of fillings, including pork and vegetables, steamed by small bamboo food steamer.

I extended my shopping to Sai Ying Pun, where I had read about a shop called Tak Chong Sum Kee Bamboo Steamer Company that sells handmade bamboo (and wood and rattan) goods.