After taking part in a latte art class in Form Four, Hui became a coffee enthusiast. He would often go to a cafe near his home in Quarry Bay, and one day, the boss noticed his passion for coffee and asked him to work for him.
"After one and a half months of working there, I decided I wanted to own my own cafe," says Hui.
Earlier this year, Hui came across Black Sheep Cafe, and discovered its owner was one of his former co-workers. He decided to buy into the cafe, becoming a co-owner.
The coffee Hui serves is not your ordinary coffee. He makes speciality coffee - or "gourmet" or "premium" coffee. According to the Speciality Coffee Association of America, a coffee that scores 80 points or above on a 100-point scale is known as speciality coffee.
With speciality coffee beans, more care is taken in choosing and looking after the growing environment. The beans are roasted for a shorter amount of time than the beans you'll find in most cafes. Beans are carefully chosen to make speciality coffee, which brings a unique flavour.
"Speciality coffee has the aroma of fruits and flowers, because the beans are roasted for a short amount of time to preserve their original flavour," says Hui.
There are three major coffee-drinking trends in Hong Kong, Hui says: instant coffee - from those ultra-convenient packets; coffee sold at corporate giants like Starbucks; and speciality coffee - where the taste of coffee is truly brought out.
Although speciality coffee is the best of the bunch, most Hongkongers are unfamiliar with it.
"My goal is to inform coffee lovers about the true meaning of high-quality coffee," says Hui. "I am going to run a series of coffee workshops with [not-for-profit organisation] Yan Oi Tong, to promote speciality coffee."
People are already catching on to speciality coffee in the United States, where consumption has increased from 1 per cent to 20 per cent in the past 25 years. Hopefully, says Hui, Hongkongers will see and taste the benefits of high-quality coffee and make the switch as well.
But trying to encourage this change isn't easy. Hui works long hours, from around 7am until 2am.
"My family is worried about my health; but this is my passion and they support me," he says.
Although the job of barista is becoming more popular among young people, Hui says few of them are able to persevere.
"We have to taste every cup before we serve it, so one must be willing to drink a lot of coffee every day," he says. "I don't eat any spicy food to keep my tongue and nose sensitive. It's not all about making coffee and creating latte art."