Tomatillos, also called tomates verdes, are small green fruits resembling the tomato but related to the Cape gooseberry. Fresh tomatillos are usually encased in papery brown husks, which are easy to peel away. The flesh has a tart, lemony flavor and is often used in Mexican sauces and stews. Choose firm tomatillos with tight-fitting husks. Refrigerate in a paper bag for up to 10 days. Canned tomatillos are found in well-stocked grocery stores.