Tomatillos, or Mexican green tomatoes, are small and green, with a thin, papery husk that should be removed before cooking.
Discard the husks and stems from the tomatillos. Bring water to a boil in a Dutch oven. Add tomatillos; cover and remove from heat. Let stand 5 minutes or until tender; drain. Place tomatillos in a blender; process until smooth. Stir in cilantro and salt. Cover and chill.
Note: Substitute 4 (11-ounce) cans tomatillos if you can't find them fresh. drain the canned tomatillos,and purée with cilantro. Omit the salt; canned tomatillos contain added sodium.