Deseed and destem the chiles de arbol. Depending on your spice level, you can leave some with the seeds in for a spicier hot sauce. Bring a pot of water to a boil.
Add the chiles de arbol, garlic cloves, and onion and boil for 15 minutes. With a slotted spoon, place the chiles, garlic, and onion in a blender.
Add the oregano, vinegar, water, salt and pepper as well. Blend until smooth.
