Sweet and spicy with a sour tinge, sriracha sauce was an instant hit when David Tran, a Vietnamese refugee, brought it to America in the 1980s under the brand Huy Fong Foods. Asian eateries were the first to snap up Mr Tran’s hot sauce, but before long the green-nozzled bottle, with its distinctive rooster logo, had become a staple in restaurants and pantries alike. Within just a few years Mr Tran went from hawking his wares out of a Chevy van in Los Angeles to walking the floor of a 20,000-square-metre factory. By 2020 his business was worth $1bn.