Boil the water and a pinch of salt over high heat.
Turn heat down to medium-high, and add the chilies and the tomatoes. Boil them for 30 minutes.
Remove the chilies, tomatoes, and a cup of the boiled water and place them in a blender.
Add the garlic and oregano as well and pulse blend until you reach your desired smoothness.
Add salt and pepper to taste.
Pour from blender into a serving bowl and refrigerate for 30 minutes before eating for optimal flavor.