Cashew, the miracle nut

Cashews were a luxury when I was growing up, only brought out on special occasions. There’s almost nothing you can’t do with a cashew. Not only does it lend its nutty sweetness to savory dishes, it also gives desserts a deep richness. In fact, it’s fantastic with butter and sugar or honey in just about any confection: brittle, fudge, halvah, spiced baklava, or cashew-caramel cake bars.

The cashew, botanically-known as Anacardium occidentale, is the seed of a tropical evergreen plant related to the mango, pistachio, and poison ivy. Originating in Brazil, the cashew plant made its way to India in the sixteenth century via Portuguese sailors. 

Unlike most fruits where the seed is found inside the flesh, the cashew seed hangs from the bottom of the cashew apple. Although the fresh cashew apple fruit is not only edible but delicious, it is only available to those who grow the plant. It is much too perishable to bring to market. Cashew apples begin to ferment as soon as they are picked and will barely last 24 hours. Cashew apples are highly prized in their growing locale, where they are sometimes found canned, in jams, or used to make liqueurs. 

The kidney-shaped cashew nut is encased in a hard shell with two layers. In between these layers is a black substance called cardol, which is extremely caustic and can cause blistering of the skin upon contact. This substance is removed during the shelling process and is used in the making of such products as varnish, insecticide, paint, and even rocket lubricant. For this primary reason, cashews are never sold in the shell.

 It is interesting to try to imagine how early humans discovered what was edible and what wasn’t. Who figured out that when you cooked stinging nettles, the sting would go away completely? How many people had to die before the relative toxicity of wild mushrooms became widely known? Who was the first human to survive a feast of fugu, the Japanese blowfish whose liver and other organs are as poisonous as cyanide but whose skin is safe to eat?

In the case of the cashew, someone, somewhere, a long time ago determined that it had to be roasted. The cashew was once nicknamed the blister nut, because if you try to eat it raw from the tree, your mouth pays the price. The cashew is not a nut, however; it’s a seed. On the tree, the fruit that contains it looks like a bloated green kidney bean or a boxing glove dangling comically below an upside-down red or yellow bell pepper, the swollen stalk of the fruit, called the cashew apple.

Just as the cashew isn’t really a nut, this so-called apple is a false fruit. Nonetheless, it’s juicy and edible, but it’s too perishable to ship, lasting only a day off the tree before becoming moldy and starting to rot, which is why it’s not sold in the United States. But in warmer countries like Vietnam, Brazil, and Tanzania, where cashew trees flourish, the cashew apple is juiced, candied, or made into jams and chutneys. Brazilians make it into wine. In Goa, India, where Portuguese sailors brought the cashew in the seventeenth century, cashew apples are trampled by foot, fermented, and distilled to make a liquor called feni.

Unlike other nuts (false or otherwise), cashews aren’t sold in the shell. That is because the testa skin, the inner lining between the outer shell (the actual fruit) and the kernel (the cashew), is toxic. A relative of poison ivy and poison sumac, the cashew contains the same rash-inducing chemicals, known as urushiols, as its kin. Heating the whole green fruit hardens this toxic stuff, allowing it to be separated from the seed. Once removed, this caustic goo is used in industrial materials such as waterproof paint, varnishes, lacquers, and brake linings, and meanwhile, cashew workers often suffer from skin and eye irritations and minor burns. The processing of cashews is therefore incredibly labor intensive, since most of the many steps—roasting, burning, boiling, soaking, cracking, and peeling—are completed by hand, labor performed by workers in factories primarily in India and Brazil.

Once rendered innocuous, the delicious, kidney-shaped little seeds, which turn from green to golden brown when roasted, are sorted, packaged, and shipped all over the world. They’re made into creamy cashew milk; rich, sweet cashew butter; and various highly addictive specialty snacks, including trail mix, Trader Joe’s Thai Lime and Chili Cashews, and Planter’s Honey Roasted Peanuts and Cashews (a double whammy of false nuts, because peanuts, of course, are legumes).

The best culinary use of the cashew, arguably, is in a dish found in just about every Chinese restaurant anywhere, from upscale Chinatown eateries to strip malls to takeout holes-in-the-wall. Cashew chicken consists of chicken-breast pieces marinated in a slurry of soy sauce and cornstarch—often also with sesame oil and oyster sauce—cooked with cashews and, usually, broccoli, onions, and/or green peppers. It’s reliably always edible, even in the most dubious of dining establishments, possibly because it’s so simple to prepare (it’s hard to screw it up), but also because cashews and chicken are one of those perfect, immortal flavor power couples, like apples and cinnamon, cheese and honey, or lamb and rosemary.

A close second for the best use of cashews is in curries, whether Indian, Sri Lankan, or Thai. The cashew’s sweet, nutty crunch is compatible with just about everything, sweet or savory: garam masala and curry spices, coconut milk, tomato paste, chickpeas or lentils, prawns, chicken or lamb, mango or raisins, almost any vegetable, and condiments such as chutneys, spicy pickles, or raita.

Cashews also are fantastic in Moroccan and Algerian tagines, with any combination of spices, sweet— fenugreek, coriander, and cardamom—or savory—garlic, paprika, turmeric, and black pepper, along with apricots or olives; chicken, lamb, or chickpeas; and preserved lemons or hot chilies.

Cashews are a major star in contemporary vegetarian cooking, too. , according to the Hindu medical treatise, cashews are very calming, incredibly nourishing, and helpful for insomnia, as well as an aphrodisiac. “I almost always have a bowl of them on our dining table,” she went on, “as a kind of insurance that my skinny boys will grab them on the fly, though it seems that mostly us thickening middle-aged folks eat them. They’re one of my favorite foods of all, my number-one nut. My favorite recipe to eat them in is a simple stir-fry that includes broccoli and peanut sauce.”

In happily-ever-after tradition, this semitoxic “false nut,” so arduous and complicated to process, turns out to be a stand-alone treat and one of the easiest ingredients to cook with.