"Having a private kitchen in the truly traditional sense is not a speakeasy without a license," Xu Yuan said. "It's somebody who has special access to some sort of special recipes and they share it with other people."
Though people occasionally complain her food doesn't have enough salt or oil, Xu Yuan said it's a waste to cover fresh food with additives.
"It just tastes better," said Xu Yuan, who also makes all her own terracotta ovens for cooking her signature duck, as well as other dishes. "Coming to a private kitchen is like eating from someone's family recipe."
While many private kitchens are located in the heart of Hong Kong near busy commerce centers and tourist attractions, newer kitchens have started opening their doors in more remote locales.
One such spot, Wong said, is Aberdeen, a town on the south side of Hong Kong Island.
"It has always been known as a more industrial zone and there has been nothing much in terms of (food and beverage) in the area," Wong said. "But because it has lower rent ... it is a perfect spot for a private kitchen to pop up."
Chef Andrea Oschetti runs Cuore -- which means "heart" in Italian -- just outside of Aberdeen.
"It is the most beautiful space in Hong Kong and I am in a very large building," said Oschetti, who invites diners into his home -- an oversized loft in an industrial building.
"A lot of restaurants in Hong Kong are very small. Even if you get a private room you don't have enough room to move around and feel comfortable."
Oschetti, who left a career as a senior manager at PricewaterhouseCoopers to explore his passion for cooking, works with his guests to customize each meal. Reservations must be made about a month in advance, but once the menu is set Oschetti has ingredients flown in from Italy for the feast.
"I don't do advertising, I only work by word of mouth ... so I cook for the people that I like and that I love."