I’ve read a lot of historical novels set in ancient Rome – by Lindsey Davis, John Maddox Roberts, Steven Saylor – and one thing they often mention in their descriptions of daily life is a fish-derived sauce known as garum or liquamen, sometimes called “fish pickle.” Apparently, to the Romans this stuff was like ketchup, they put it on everything. But what was it like? From the novels I’ve always pictured it as something like anchovy paste. But I’ve seen “fish sauce” in Vietnamese restaurants that’s nothing like that, it’s a clear liquid (that tastes like fish).
(Not sure if this belongs in CS or GQ – I’m putting it here since it’s about cuisine.)