Combine all the ingredients except cilantro in a pot and bring to a boil. Cover, lover the heat, and simmer for about 10 minutes or until the tomatillos are soft. Remove from the heat and allow to cool. Transfer the cooled ingredients and the liquid to a blender. Add the cilantro, and puree until smooth and uniformly green. Refrigerate. Makes about two cups. Serve cold or at room temperature. It's wonderful served with grilled meats....a pork chop, for example. It's also very nice mixed with some yogurt to toss with hot pasta for a low-fat quick dinner. And stir some into some soup; it will perk up almost anything without being overwhelming.