Toast the chiles: Add the chiles to a dry 12-inch frying pan. Turn the stove to medium heat and gently toast the chiles, flipping halfway during toasting, 4 to 5 minutes. The exterior of the chiles will take on a dark color, and you'll start to smell their aroma. Once the chiles are toasted, remove them from the pan and allow them to cool for 10 minutes (or until cool enough to handle).

Stem, seed, and soak the chiles: Once the chiles are cool, pull off their stems. After pulling the stems, you can easily tear them open. Shake out the seeds inside and pull the yellow (or white) membrane that lines the inside of the peppers. Put the peppers in the jar of a 64-ounce blender and carefully pour the boiling water or stock over them. Allow the peppers to soak for 15 minutes.

Puree the sauce: Check to see that the peppers have softened. Remove 1 cup of the soaking liquid and set aside. Add the chopped tomatoes to the blender, along with the onions and garlic, salt, oregano, cumin, and (if using) ground cinnamon and cocoa powder. Blend on high speed until smooth, 30 seconds to 1 minute. Use a rubber spatula to scrape down the sides and blend once again at the same speed for another 30 seconds. Taste the sauce; the heat level will depend on the chiles you used. If desired, add some chipotle peppers for more heat or flavor. If you’d like the sauce to be thinner, add as much of the reserved soaking liquid as needed.

Use or store: Taste for seasoning and add more salt, if needed. The sauce is now ready to use. Did you love this recipe? Give us some stars below!