
From Hong Kong to London: In 2016, I quit my full-time job and opened a street market stall selling bubble waffles -- aka egg waffles -- under an undersized tarp one cold winter in London.

Why bubble waffles: The move was a response to my experience a year earlier, when I tried a re-invented bubble waffle in a street food market for the first time. Disappointed by its taste, I decided to sell my own version.

The classic: Called "gaai daan jai" in Cantonese, bubble waffles are crispy on the outside, while the inside of each "bubble" is fluffy. It's an unexceptional cheap street food that can be found everywhere in Hong Kong.

The new bubble waffle trend: Bubble waffle shops serving jazzed-up versions have been popping up around Europe in the last few years.

Instagrammable desserts: The new bubble waffles are rolled into a cone then stuffed with ice cream and other colorful toppings.

Oleg Sabsai: Arguably the most influential person to bring forth this new wave of bubble waffle desserts isn't a Hong Kong migrant, but Ukrainian entrepreneur Oleg Sabsai, founder of the Bubble Waffle Network.

Choy Tung Shing: Leung Wing Cheung, the third-generation owner of Choy Tung Shing -- one of the oldest blacksmith shops in Hong Kong -- says it's impossible to find the true origin of the 1950s snack. "Are you sure you want to write about egg waffles? Why not char siu (barbecue roasted pork) or something more remarkable?" Leung asks me.

Retired Hong Kong bubble waffle master: In the 1960s and 1970s, the city was experiencing an economic crisis, alongside an influx of new immigrants from mainland China. Many turned to hawking as a means to make a living, including Lee Sui Yuen, who just happens to be my bubble waffle teacher. "To make a good waffle, you need to have good ingredients, good techn