In the United States, Cinco de Mayo is an excuse for margarita-fueled partying. But in Mexico, that date—the anniversary of a military triumph over Napoleon on May 5, 1862—is marked by a parade and not much else. The real celebrations happen on September 16, which is Mexican Independence Day. At Gastropod, we’re always down to party, so here’s to Mexico’s true national holiday, and its true national dish: mole. But what is mole? Listen in this episode as we trace mole’s complicated evolution from medieval Moors to the invention of the blender, and from something that had been considered peasant food to a special-occasion showstopper.

Rachel Laudan is a food historian and the author of Cuisine and Empire: Cooking in World History—but, when she started researching mole, the first document she uncovered was hardly deep in the archives. When she first visited Mexico, in the 1990s, Laudan went to a restaurant famous for its mole. “And, of course, they had the statutory place mat with the story of mole poblano being invented in a convent in the 18th century,” she told us.

According to the origin story on the place mat, some nuns, in a panic because an archbishop was visiting and they had nothing to serve him, threw a bunch of spices in a pot and somehow came up with the perfect rich, chocolate-brown sauce. “That, to me, just sounds like propaganda,” says Fernando Lopez, one of three siblings whose father founded Guelaguetza, an Angeleno restaurant that is a temple to Oaxacan mole. He believes mole is far too complex to have been created overnight. Plus, mole comes in many varieties and colors. Guelaguetza serves six kinds of mole—mole negro, mole rojo, mole coloradito, mole amarillo, mole verde, and mole estofado—but Sandra Aguilar-Rodriguez, an associate professor of Latin American history at Moravian College, in Pennsylvania, told us that she could name 10 versions off the top of her head, and that each town in the south of Mexico has its own variations on the classic recipes.