SINGAPORE -- It is early afternoon at Singapore's largest shopping mall in April, and the line at the Irvin's Salted Egg stall is ticking over at a manageable half-dozen.
There is no late-lunch rush -- not by Irvin's Salted Egg standards -- where customers often face limits on the number of bags they can buy filled with Irvin's signature snack -- chips made from the deep fried skin of a John Dory fish flavored with salted egg yolk.
Rich, sweet and habit-forming, salted egg yolk -- an ingredient that has long been used in small quantities as a condiment in Southeast Asia -- has, over the past few years, become ubiquitous in Singapore.
Last year, Singapore imported more than 3,000 tons as the flavor found its way into everything from potato chips to bubble tea. Even global brands got in on the act, with Domino's offering pizza topped with salted egg and cheese sauce, and McDonald's rolling out salted egg yolk fries.
Launched in 2015, Irvin's Salted Egg got in at the ground floor, even though founder Irvin Gunawan had no concept of just how rapidly it would take off.
"I think for so long Singapore didn't have anything new, and then this came along. It was in everything -- ice cream, chocolates, it was crazy," Gunawan told the Nikkei Asian Review in an interview at his company's headquarters on an industrial estate in Singapore's Ang Mo Kio district.
In four years Irvin's Salted Egg has grown from one tiny kitchen with three employees to 300 people spread across 21 outlets in six countries.
Born in Indonesia, Gunawan, 33, came to Singapore as a child after his parents fled the turmoil that followed the collapse of the Suharto regime.
After attending university in Australia, he returned to Singapore to set up an Indonesian restaurant in the city's central business district, a notoriously difficult place to run a food and drink business, with its high costs and limited footfall outside of office hours.
"It's a killer," said Gunawan. "Those who make it, I salute them."
Gunawan's first restaurant shut down after two years, but he soon opened a second focusing on Malaysian and Singaporean seafood.
It was there that he started to sell salted egg chips, first offering them as a side-dish on the menu, then as a packaged snack that customers could take away -- another revenue stream, thought Gunawan, that could help bolster a struggling business.
"Then it was just a matter of survival," Gunawan said. The restaurant eventually closed, but the chips kept on selling as his customers begged him to keep on making them.
When Gunawan opened a pop-up store in Singapore CBD, lines quickly formed at the booths as customers raved about the snack on social media. The business soon took on a life of its own. More pop-ups followed, but the watershed moment was opening a permanent storefront at VivoCity, Singapore's biggest shopping mall.
"Suddenly [the chips] reached the Indonesian and Filipino [tourists]," Gunawan said. "It fits their taste buds. It's sweet, salty, strong-tasting, so it exploded in those two countries."
Today, Irvin's Salted Egg customers in Singapore are tourists -- and Gunawan's flagship store is now located at Changi Airport to cash in on international demand.
Reluctant to disclose hard numbers, the company did reveal that around 70% of customers are aged between 20 and 40 years old. And of that, around 70% are women. Overall, sales have tripled since 2017.
Irvin's has now has four outlets in the Philippines, four in Hong Kong, and two stores each in Taiwan, South Korea and Thailand. Buyers from Indonesia come to Singapore to stock up and resell the product online back home.
"It's a very organic way of distribution," says Gunawan. "These days you cannot control how people distribute anyway, and [online resellers] have been a very big part of the marketing as well."
The growth of e-commerce in Southeast Asia means that Irvin's does not have to expand its physical footprint to grow its business, he added. "I don't think we'll have tens of stores in each country. That's not how the model works."
Physical stores might work as marketing tools, but Gunawan says the majority of customers will get the product through resellers online.
"It's not like 30 years ago, people can always buy online," says Gunawan. "You need to have a good distribution hub, but nowadays you only need a few stores and then the rest [of the customers] you can reach online."
Despite its growing reach in Asia, the company intends to continue making the product Singapore, rather than shifting production to lower-cost locations elsewhere in the region.
Producing in Singapore gives a certain expectation of quality, said Gunawan, which means that people are willing to pay a premium for the product -- 15 Singapore dollars ($11) for a 230 gram bag -- while higher costs are offset by government financial support.
"The government here really wants you to grow. They are big stakeholders in any business here in Singapore," he said. "There's a lot of grants, especially for machines."
Irvin's Salted Egg is privately owned, and has not taken on any investment money, preferring to bootstrap and grow organically. It also has some claim to being a family business, with Gunawan's brothers now both part of the company, one as CFO and the other as operations manager.
Tight-lipped about future plans, Gunawan said that despite the rapid growth of the business and his own profile, he is not looking to cash in.
"Honestly speaking, we never talked about selling this brand to any investors. We enjoy doing this," he said. "We enjoy being in control of everything that we do. Honestly speaking, we just want to be able to have our space to create products and sell it to the market.
For now, Gunawan says the company will work on developing new products. In the first instance, that means more items coated in his signature salted egg, but in the longer-term, it means spotting the next big food wave before it breaks.
"The issue now is about creating a new thing -- creating the next Irvin's," Gunawan said. "Because we can't stand still and expect this to last for the next 10 years. We want to create the next wave as well."
--Nikkei staff writer Justina Lee contributed to this report.