Preheat the broiler. Place the tomatillas on a baking tray and broil, turning frequently until slightly charred, 15 minutes. Set aside to cool. In a saucepan combine water, garlic, chiles, onion and cilantro and simmer until chiles are tender. In a blender combine tomatillas and simmered mixture and process to desired consistency, but not liquified. Transfer salsa to a bowl and add salt and 1/2 teaspoon sugar, to taste.
Blend until pureed, but not liquefied.