Atapakua is a Purhépecha term that refers to whole range of stew-like dishes thickened with masa. In this atapakua from Imelda Campos Sebastián (also known as doña Mela) of Michoacan, Mexico, sorrel adds bright acidity to a masa-thickened sauce made of a blend of seeds and vegetables. Greens like mature arugula, mustard greens, or Swiss chard can stand in for sorrel in this dish but will lack its punchy flavor. (If substituting heartier Swiss chard or mustard greens for sorrel, remove the stems before using). Doña Mela doesn't serve this dish with lemon, but if sorrel is unavailable, squeeze in a few drops of lemon juice before serving. Yerba buena, similar to orange mint, has a citrusy, minty flavor with notes of pine; look for it or orange mint at Mexican grocery stores or at plant nurseries.
Pipián can be prepared through step 6 and cooled, covered, and refrigerated up to 1 day ahead.
To substitute masa harina for fresh masa, stir together 1/3 cup (1 1/8 ounces) masa harina (we tested with Masienda brand) and 1/4 cup water. Whisk together with an additional 1/4 cup chicken stock or water before adding to the pipián.
Traditionally, the seeds and nuts in this recipe are ground using a metate, a grinding stone made from volcanic rock similar to a mortar and pestle. This tool is the heart of many of Mexico's Indigenous kitchens. ($130, mexgrocer.com)