Guzman y Gomez has had a volatile run since listing on the ASX. But its founder and boss is looking beyond short-term market pressure, with big plans for the chain's US expansion.  Sean Aylmer speaks with founder and co-CEO Steven Marks about building a “generational” fast food brand. Marks discusses the challenge of cracking the US market, the role of drive-thrus and delivery, and the company's focus on food quality, speed and value.