Tomatillos, green chilli, onion and coriander, boiled or charred and blended — sharp, green, on everything.
What makes it salsa verde
Tomatillos, not green tomatoes.
Serrano or jalapeño for heat.
Raw onion and coriander blended in at the end.
Where it comes from
Salsas are older than the conquest, ground in a molcajete, the volcanic-stone mortar still used today. The green one is built on the tomatillo, a husked relation of the tomato domesticated in Mexico.