Remove stalks if any from the dried chiles and discard. Wipe the chiles with a damp cloth to remove any dust. Heat the oil in a frying pan and gently fry the chiles, without burning, turning them around from time to time until they are firm to the touch, about 5 minutes.

Remove the chiles with a slotted spoon and drain on paper toweling. In the same oil, fry the tomate verde and garlic until lightly browned and soft inside, about 5 minutes. Put the water into a blender jar add the tomate verde, peeled garlic, and crumbled, fried chiles with their seeds and veins. Blend for a few seconds to a textured puree. Heat the same oil in the pan, add the onion and fry gently until translucent, without browning--about 1 minute. Add the blended ingredients and salt and fry, stirring form time to time and scraping the bottom of the pan, until the sauce has reduced and thickened a little and is well seasons--about 5 minutes.