There are so many Mexican dishes that call for epazote (almost as many as the ones calling for cilantro), that I realized just how stellar herbs can be in defining a dish ... click on image for more
I always thought onions arrived in the Americas from the Old World, but since they were sold in Mexican (Aztec) ancient markets, and have a Nahuatl name, it is probably fair to assume that many recipes for salsa, guacamole, and stews from pre-Hispanic times already had onions on their ingredient lists ... click on image for more