Mexicans can tell that this is not something you often find in cities. Instead, it’s what men who toil on farms buy in local street markets or get from their wives before they head to work, because it keeps well even in the high heat of the afternoon. When they need a snack, they break out tostadas (crunchy corn tortillas) and spread on chintextle, the potent paste turning even that simple snack into a real treat.

1 1/2 ounces pasilla de Oaxaca chiles (9), wiped clean and stemmed
4 ounces hulled raw (green) pumpkin seeds (¾ cup)
5 large garlic cloves, peeled
2 tablespoons rice vinegar
2 tablespoons distilled white vinegar, or more to taste
1/2 teaspoon fine salt, or 1 teaspoon kosher salt
1 to 2 tablespoons mild olive oil or vegetable oil, if necessary

Heat a comal, griddle, or heavy skillet over medium-low heat, and toast the chiles a few at a time, turning them over and pressing them down with tongs frequently, until they become a lighter shade of brown and develop some blisters, about 2 minutes per batch. Set them aside to cool. Heat a skillet over medium heat and toast the pumpkin seeds, stirring and tossing constantly, until they’re puffed and just slightly browned, 5 to 8 minutes. Transfer them to a plate to cool. Put the chiles, pumpkin seeds, and garlic in the food processor (there’s not enough liquid to use the blender here) and process to form a paste, scraping the sides often. Add the vinegars and process again. Season to taste with the distilled vinegar and salt, and process again to blend. If necessary, add oil, a little at a time, to help blend the mixture into a very smooth paste. Processing will take at least 3 minutes total. Before you serve it, refrigerate the chintextle in an airtight container for one day to allow the flavors to develop.