“It tasted very much like American Chinese food, it was too sweet. The texture was very gloopy, very sticky, and I think it was a little bit too out there for an American audience. If you eat chicken nuggets, you have barbecue sauce, you have hot mustard, but you don’t have this vaguely Asian style sauce. It was a novelty,” recalls Pang.

Interest in the sauce soon dissipated and it was forgotten until 2017, when an episode of cult adult cartoon show Rick and Morty – which featured a mad scientist and his adventures with his grandson – mentioned the SzeChuan sauce.

“The show began with Rick in this hallucinogenic dream sequence. He was dreaming that he was at McDonald’s to taste the SzeChuan sauce before it went out of circulation,” explains Pang. “And so for the remainder of the show, it became this running joke, that all he wanted was to bring back the SzeChuan sauce.”

Fans of Rick and Morty began demanding the return of SzeChuan sauce, and a few months later, McDonald’s announced it would be revived – but for one day only – on October 7, 2017.

However, on the day, the fast-food chain was completely unprepared for the onslaught of people who turned up to get their hands on the sweet, Asian-style sauce.

Each McDonald’s only had two dozen packs of the sauce to give away, and customers who had queued for hours were very angry, shouting: “We want sauce!” At one outlet in Newark, in the American state of New Jersey, the police had to be called in to calm things down.

Sachets of the sauce have appeared on eBay selling for up to US$250 each.

However, the sauce created by McDonald’s lacks any authentic Sichuan flavour. Sadly for fans of the too-sweet McDonald’s sauce, there is no such thing as a generic “Sichuan sauce” in the Chinese province, says cook and food writer Fuchsia Dunlop.

“A really good Sichuan meal is like a roller-coaster ride – you have spicy notes, sweet and sour notes, numbing and gentle flavours,” says the British cook who has been researching Chinese cuisine for 25 years. That’s a far cry from what McDonald’s was trying to emulate.

Sichuan cuisine is one of the eight great cuisines of China and is famous for its fiery dishes. But Dunlop says it’s a common misconception that the cuisine focuses only on heat.

Dunlop studied in Sichuan in the mid-1990s and was the first Westerner to train at the Sichuan Higher Institute of Cuisine. She was won over by the “stimulating, dramatic and exciting” cuisine during her first trip to the Sichuan capital, Chengdu, in 1993, and has gone on to write six books about Chinese food and culinary culture, two of which are about Sichuan.

“The really interesting thing about Sichuan cuisine is its diversity of flavours. When I was studying to be a chef there, we learned 23 complex flavours. It is like French classic sauces, but with different balances of sweet, sour, spicy and tingly,” she says.

One of the most well known attributes of Sichuan cuisine is mala, which refers to the numbing and tingling sensation caused by Sichuan pepper (ma) and the heat from the chillies (la).

“Sichuan pepper is what makes Sichuan cuisine different from other spicy cuisines like Hunan, where they use a lot of chilli but don’t use [the numbing Sichuan pepper],” says Dunlop, who is releasing a new and updated edition of her first book, The Food of Sichuan, in October.

The numbing properties are believed to be caused by the molecule hydroxy-alpha sanshool, found in the outer shell of the berry.

While Sichuan is one of the most popular regional cuisines in China, it only really caught on in the West 20 years ago, says Dunlop. “From the 1990s Sichuan food took off – you had all these people from all over China going to live in America and England and they wanted to eat their favourite food, which was Sichuan food.”

They had a business in the city making doubanjiang, a thick chilli paste that’s another key ingredient used in Sichuan cooking to make spicy, hot dishes. While there is no sauce called Sichuan sauce anywhere in China, doubanjiang is the paste that is definitely the soul of Sichuan food and is crucial for dishes such as mapo tofu.

Chan started cooking at the age of 12, and apprenticed in Huaiyang cuisine, building a strong foundation in knife skills before learning Sichuan and Cantonese cuisines. Throughout his over 50-year culinary career Chan has cooked Sichuan food in various countries, including Singapore, Malaysia, Thailand and Canada.

He finds the fiery cuisine more difficult to learn how to cook because of the various combinations of chillies that can be used to elicit layers of spice.

“Sichuan cuisine allows your taste buds and the tip of your tongue to feel a ‘dancing sensation’. But not all Sichuan food is spicy – it can have surprisingly different kinds of spice, some that are mild, some that are extra hot, and their aroma can change depending on if they are cooked with meat or seafood. A spice that seems to be light in taste can have a very long, but strong aftertaste that hits you hard,” Chan says.

He also likes the fact that chillies not only taste sweet and spicy, but give diners a physical sensation due to the numbness of the tongue.

“Only one-third of Sichuan cuisine has spiciness in it. The reason why Sichuan food has varying levels of spice is because the province’s food is a mix of culinary styles, as immigrants from neighbouring provinces brought different eating habits and cultures,” Chan says.

In the middle of the 17th century, a peasant rebel leader called Zhang Xianzhong, from present-day Shanxi province, led his peasant troops south, and conquered what we know today as Sichuan province. He declared himself emperor of the Daxi dynasty, and massacred a number of people in Sichuan.

This led to many years of turmoil during the transition from the Ming dynasty to the Qing dynasty in China, which resulted in the population of Sichuan falling sharply. To that end, Chan says people from neighbouring regions such as the present-day provinces of Hubei and Hunan were forced to resettle in Sichuan, and brought with them culinary traditions that involved a lot of spice.

The most refined Sichuan dishes are not spicy at all, such as ji dou hua, a chicken-flavoured dish of soft bean curd that dates back to the Tang dynasty around 1,300 years ago.

As a result the elite did not eat many of the fiery hot dishes, as chillies were considered to be peasant food.

Chan is keen on introducing and educating Hong Kong palates to Sichuan cuisine and its complex layers of spice.

“Sichuan cuisine is considered aggressive in China. The flavours are so irresistible that after eating your first Sichuan dish, you slowly become addicted,” he says. “Over the last 20 years, Hong Kong has seen an influx of immigrants from China who have integrated their various food cultures into the local dining scene. This has allowed people in Hong Kong to open their taste buds to the incredible flavours that Sichuan cuisine has to offer.”