Rinse the chile pods 5 times, then let soak in water in a bucket or large bowl for 5 hours or so.
After the chiles have soaked for 5 hours, discard the water. Put the chile pods in a blender. Tamp the pods down into the blender, then add water to the top. Blend well into a paste.
Put the paste in a large saucepan over medium heat.
Make a roux. Put the oil in a saucepan, over medium heat, heat up slightly, add the flour and stir constantly. The flour should get toasted and brown, but do not burn it, about 5 minutes.
Drizzle the roux into the red chili and mix to combine. This will make it thicker and change the color slightly, but it should not get white in color. The chili and liquid should just look darker and less bright than the red chili without any roux. Add enough roux and water to get the chili to the right consistency, which should be like gravy. You may not use all the roux.
Add the garlic and salt. Leave the chili in the pot to simmer for 20 minutes, stirring regularly. Do NOT bring it to a boil, as that may burn the flour in the roux. Add more salt and garlic if needed and serve.
The paste can be frozen in small batches for later use.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.