Prepare the Peppers: Start by roasting the dried Ancho and Guajillo peppers in a dry skillet over medium heat for about two minutes. Once roasted, remove the seeds from the peppers.
Soften the Peppers: Place the roasted peppers in boiling water or chicken broth for 30 minutes to soften them.
Roast the Vegetables: While the peppers are soaking, preheat your oven to 400°F (200°C). Place the quartered onion, tomatoes, and peeled garlic cloves on a baking sheet lined with parchment paper. Roast the vegetables in the oven for about 20 minutes, or until they are softened and slightly charred.
Blend the Ingredients: After the peppers have softened and the vegetables are roasted, add them to a high-powered professional blender. If desired, include optional Arbol peppers for extra spice. Blend the mixture until smooth.
Cook the Sauce: Transfer the pureed mixture to a medium saucepan. Stir in the dried oregano, kosher salt, and ground cumin. Simmer the sauce over low heat for about 30 minutes, allowing the flavors to meld together.
Adjust the Flavor: Taste the sauce and if it's bitter, add the optional brown sugar to balance the flavors. Stir until the sugar is fully dissolved.
Strain the Sauce (Optional): If you prefer a smoother sauce, strain it through a fine mesh strainer to remove any tomato or pepper skins.
Enjoy: Once the sauce is smooth, flavorful, and ready, it's time to enjoy it in your favorite