Rince the chile pods under running water to wash off any dust or dirt.
Break off the tops of 12-15 dried red chile pods and dump out the dry seeds.
Add the red chile pods to 3 1/2 cups of water in a saucepan and bring to a boil. Allow them to boil for about 10 minutes, then cover and turn off the heat and let them sit for another 10 minutes.
Scoop out the rehydrated chile pods with a slotted spoon and add them to a blender with 1-2 cloves of garlic. Then add about 1 cup of cooking liquid. Puree on high for about 1 minute, then slowly add the remaining cooking water.
In another pan, heat 2 tablespoons of oil mixed with 3 tablespoons of all-purpose flour. Stir with a whisk until well combined and bubbly. (This is your roux that will thicken the sauce and give it a slightly creamy texture.)
Put a foley food mill or wire mesh strainer over the roux to strain the pods and seed. Slowly add the pureed red chiles to the strainer about 1/2 cup at a time stirring the roux well between each 1/2 cup of liquid added.
Continue until all of the liquid is added then crank the food mill or press on the chile pods with the back of a spoon to get out all of the remaining liquid.
Add 2 teaspoons of oregano and 1 teaspoon of salt to the chile sauce and simmer on low for about 5 minutes before turning off the heat.
Notes
Be careful blending the cooked chiles and the hot water, it can overflow out of the top of your blender.
You can also use an immersion blender and puree them directly in the cooking pot, but if you are using hot or extra hot chiles, the spice will get into the air and make you cough.
Don't touch your eyes or face when handling the chiles or making the sauce. They are very spicy and will burn your eyes.
Some chiles have a bitter flavor if they get old or too dry. If your chile sauce is bitter, add a small amount of sugar or agave nectar to it. You can also use 3 cups of fresh water when blending and discard the cooking water.