For best flavor, plan to make the sauce a day ahead and refrigerate so the flavors can fully develop.

Rinse the dried chiles under cold water to remove any dust. Cut off the stems and shake out the seeds if desired.

Place the chiles in a bowl and cover with boiling water. Weigh them down to keep submerged and soak for 20 minutes to 1 hour, until softened.

Lightly toast the chiles in a dry pan until fragrant, being careful not to burn them.

Roast the onion and garlic on a sheet pan at 400°F for about 10 minutes, until slightly charred.

Drain the chiles and add them to a blender with the roasted onion, garlic, and some of the chicken broth. Blend until completely smooth.

In a Dutch oven or large pot, heat the olive oil over medium heat. Add the flour and cook, stirring constantly, until golden brown, about 5 minutes.

Pour in the chile puree, whisking well to combine and prevent lumps. Simmer for about 5 minutes.

Stir in the apple cider vinegar, oregano, and salt. Continue to simmer for about 15 minutes, stirring occasionally.

Add more chicken broth as needed to reach your desired consistency. Taste and adjust seasoning, adding more salt or even a pinch of sugar if the sauce tastes slightly bitter. Add more bouillon if needed for deeper flavor.

Let the sauce cool, then store in the refrigerator until ready to use. The next day, reheat gently and enjoy in your favorite dishes.