Tomatillos a summer treat with punch

This summer season, as your eyes grow wide at the sight of ripe, plump tomatoes at your local farmers' market, look for their cousin, the tomatillo. Just as its English translation describes, the tomatillo is a small, green tomato that brings a refreshing punch to a summer salsa or stew.

Like their relatives, tomatillos are a member of the Solanaceae family, botanical fruits of the plant that they are grown from. Native to Mexico, tomatillos are also referred to as "tomates de cascara" because they grow inside a pale green husk that often cracks as the tomatillo grows inside it.

While you'll mostly see toma verdes, two other varieties of tomatillos are de milpa and purple, the latter - you guessed it - a purple tomatillo.

Tomatillos date as far back as 800 B.C. and were considered a staple in Aztec and Mayan cuisine. Some sweet and some sour, they grow anywhere from an inch in diameter to the size of an apricot. As well as being juicy and delicious, they are a source of vitamin C, fiber and potassium.

How to select: Although a sign of unripeness with tomatoes, a green or yellow tomatillo suggests it is at the peak of its season. Smaller ones tend to be sweeter than the larger, and the tomatillos should be firm and free of defects. The husk is also a great indicator of freshness; it should be light brown and not shriveled or dry.

How to use: Tomatillos can be eaten raw or cooked. They are usually pureed and used in salsas, other styles of sauces and stews. Raw tomatillos have a fresh, citrus taste and cooked tomatillos have a mellower flavor. Husks are useful as well; when infused in water, their acidic quality can act as a leavening agent for certain doughs such as tamale masa.

How to store: If you grow your own tomatillos, they are best stored in a cool, dry area. Purchased tomatillos are best stored with their husks removed in plastic bags kept in the refrigerator and can last up to three weeks.

Anne Dolce is a graduate of the California Culinary Academy. E-mail her at food@sfchronicle.com.

This article appeared on page K - 7 of the San Francisco Chronicle