Courtesy of Diana Kennedy, From From My Mexican Kitchen: Techniques and Ingredients
This sauce is a great table salsa and goes well with tacos, grilled meats, burritos, and grilled vegetables. It will last for a few days in the refrigerator.
1 pound tomatillos, husks removed and rinsed
3 or more jalapeno chiles, finely chopped
½ cup loosely packed, roughly chopped cilantro
1 garlic clove, roughly chopped
2 tablespoons white onion, roughly chopped
Salt to taste
Put the tomatillos whole in a small saucepan, barely cover with water, and bring to a simmer. Lower the heat and continue cooking until soft but not falling apart, about 5 minutes, depending on the size. Drain over a bowl to reserve the cooking water!
Using a blender or food processor, put 1/3 cup of the cooking liquid in the processor bowl. Add the chiles, cilantro, garlic, onion and grind to a paste. Add the tomatillos a little at a time, blending with about 1/3 cup more of the cooking liquid until you have a textured sauce of medium consistency. Add salt to taste.