Full of such physical contrasts, the tomatillo is the duck-billed platypus of the produce stand.
Mexican cookbook author and teacher Diana Kennedy has called them "one of the most fascinating ingredients in Mexican cooking." Rick Bayless, author of Mexico One Plate at a Time says that tomatillo salsa "transports you straight to Mexico. It is the gustatory essence of the country."
This is high praise for the small green fruit that lost out to tomatoes in terms of global popularity. But the tomatillo reigned supreme in Mexican cooking long before European colonization. Today, it is an ingredient unique to Mexican cuisine and, because of this, is one of the few ingredients that really define the Mexican kitchen.
The tomatillo is such a wonderful reflection of Mexican food today because it is still distinctively Mexican. Corn may be the most important ingredient in Mexico, but today it is well-traveled and has reached far beyond Mexico's borders. Chilies and tomatoes have circled the globe and are staples throughout the Far East and Mediterranean.
The tomatillo was never as adventurous (they are hard to come by outside North America), yet its lemony tart flavor, with hints of apples and herbs, is nothing short of essential to Mexican cuisine. The bright green salsa verde, based on tomatillos, is added to tacos, tamales, soups, and egg dishes. It is also the base for green sauces used for simmering meats, seafood, and vegetables. Exaple: Puerco en salsa Verde, or Tacos de chicharron ( pork skin ) en salsa verde.
The tomatillo is a member of the nightshade family, which includes tomatoes and eggplants. First cultivated by the Aztecs, tomatillos are smaller (about the size of a golf ball) and less juicy than tomatoes. Though they are usually used while green, as they ripen tomatillos turn yellow and then purple. In fact, Rick Bayless suggests using smaller, yellow ones if you can find them.
The fact that tomatillos never spread beyond the Americas is a bit puzzling, since they are much more durable and user-friendly than tomatoes. Because they are less affected by insects and disease, they provide a steadier crop.
Tomatillos should be cooked before using, though some Mexican sauces call for them to be blended raw. Quick boiling or roasting will allow the fruit to release most of its flavor. Wrapped loosely in a paper bag, they can last a few weeks. Do not store them in airtight plastic, however, as they will spoil quickly.