The early Chinese immigrants in the US were mostly from Toisan, a rural Cantonese county in southern China. The coastal community had a tradition of sailing abroad but was experiencing bloody ethnic conflict and economic struggles, which prompted waves of immigration to America.By the time Mr Chan had his first tastes of chop suey, there were relatively few Chinese Americans in the US - 0.08% of the total population - most of whom were descended from Toisan.

"It was like if all the Americans in China were from a small town 100 miles outside of Los Angeles. Very underrepresented," said Mr Chan. As a result, early American-Chinese food tended to be homogenous, had to adapt for local ingredients and catered to an Americanised taste.