01 - Toast dried ancho chilies in a dry skillet over medium heat for 1-2 minutes, turning until fragrant. Transfer chilies to a bowl, cover with hot water, and soak for 15 minutes until softened. Drain, then roughly chop the chilies.
02 - Heat olive oil in a saucepan over medium heat. Add chopped yellow onion and peeled garlic cloves, sautéing until translucent, approximately 5 minutes.
03 - In the saucepan, combine the soaked ancho chilies, fire-roasted diced tomatoes, tomato paste, brown sugar, molasses, apple cider vinegar, water, smoked paprika, ground cumin, kosher salt, black pepper, ground coriander, and cayenne pepper (if using). Stir well to integrate all components.
04 - Bring the mixture to a simmer. Reduce heat to low, cover, and cook for 20 minutes, stirring occasionally, until the sauce has thickened and the flavors have melded.
05 - Remove the saucepan from the heat. Utilize an immersion blender to puree the sauce until smooth. Alternatively, carefully transfer the contents to a countertop blender and process until smooth.
06 - Taste the sauce and adjust seasonings as necessary. Allow the sauce to cool completely; it will become thicker as it cools.
07 - Transfer the cooled sauce to a sealed container and refrigerate for up to 2 weeks.