• Cut the tomatoes, chilies and onion in half. Remove the stem from the chiles. Place everything on a tray and pour the teaspoon of oil on top.
• Place in the oven and cook in the broiler setting for about 5-7 minutes, or until the skin begins to brown. Flip 1 time during this time so everything grills evenly.
• Remove everything from the oven and let it cool for a few minutes. Immediately place it in the blender, add grain salt to taste. Blend lightly.

Pour the sauce into a container, add the water and chopped cilantro. Stir and adjust the salt.

It serves.