Soak the chilies in 8 cups water for a couple of hours, until softened.
Remove the chilies from the water, reserving the soaking liquid. Remove and discard the stems and seeds and coarsely chop the chilies. (You should have a good cup.) Strain the soaking liquid and set it aside.
Sauté the onions and garlic in the olive oil in a large saucepan for 3 to 4 minutes, until blond in color. Add the chopped chili peppers and cook for about 1 minute, then add the tomatoes, reserved soaking liquid, oregano, and salt to taste. Bring to a boil, reduce the heat, partially cover, and boil gently for 30 minutes.
