Pesto made in a food processor: Not so traditional, but oh, so practical. (Dixie D. Vereen/For The Washington Post)

Roberto Panizza is not amused by the pesto I describe, one I make at home with arugula, pumpkin seeds and aged Gouda cheese. He ruefully shakes his head. “I like pumpkin seed. It sounds like a nice sauce,” he says, still shaking his head. “But it is not a pesto.”

We’re sitting at a table in Panizza’s trattoria, Il Genovese, considered by many to be the high temple of pesto in Genoa, the Ligurian city that is the undisputed spiritual capital of the sauce. Pesto, in fact, is a candidate to become protected by UNESCO as an “Intangible Cultural Heritage.” To say that Panizza, organizer of the biannual Pesto World Championship, is a traditionalist would be an understatement. “Pesto is part of my life,” he says. “Pesto is not just a sauce. It’s a technique. It’s a part of culture. The ingredients tell a grand story.”

To Panizza, those ingredients are non-negotiable: special Genovese basil that’s grown only in Liguria; special garlic that’s grown only in the small village of Vessalico; Parmigiano-Reggiano and Sardinian pecorino; the highest-quality extra-virgin olive oil, salt and pine nuts. Basta così. As for technique, he insists that a pesto must be ground by a wooden pestle, using a circular motion, in a marble mortar. The word pesto, after all, derives from pestare, meaning to pound or crush. At Il Genovese, the marble mortar seems the size of a small bathtub, the pestle the size of a softball bat. I don’t even bother to ask about using a food processor. I already know Panizza’s answer: No.

Gemelli With Mint Parsley Pistachio Pesto. (Deb Lindsey /For The Washington Post)

Panizza is still shaking his head about the pumpkin seeds and arugula, and says, “That would be like presenting, for your American Thanksgiving, a chicken and no turkey!” We tuck into a huge platter of testaroli (somewhere between a pasta and a crepe) smothered in Il Genovese’s amazing, velvety — and “correct” — pesto. It’s like going to pesto church, and it’s hard to argue with tradition.

Hard, but not impossible. So I’m going to argue with tradition. I’m not the only one. Massimo Bottura, Italy’s star postmodern chef, recently offered a recipe for pesto using — gasp — bread crumbs and herbs salvaged from the scrap heap instead of pine nuts and basil. That was during Milan Expo 2015, as part of a pop-up charity he ran to feed the homeless. Now, Bottura serves it in his restaurant.

Of course, here in the United States, we’ve never really cared about tradition and never needed an excuse to fool around with such a dish (recall sun-dried-tomato pesto?).

American pesto is a funny phenomenon. The first pesto recipe published in a U.S. magazine was in Sunset in 1946. It still took another three decades to catch on, not garnering more than a handful of mentions in the New York Times, for instance, until the mid-1970s. Then, in the early 1980s, pesto’s popularity exploded. Its staying power as a food trend lasted well into the early 2000s. By then, pesto was old hat. You could have it slathered on a chicken salad at McDonald’s.

A further challenge to traditional pesto is the recent news that the pine nut industry might be destroying an ecosystem in Russia’s far east, where the Korean pine tree is unsustainably harvested. In October, Jonathan Slaght of the Wildlife Conversation Society wrote an op-ed in the New York Times, pleading with home cooks to stop using pine nuts. “The Korean pine nut pesto you eat today thus carries with it an unseen cost,” Slaght wrote.

Pappardelle with Arugula Pumpkin Seed Pesto. (Deb Lindsey/For The Washington Post)

Beyond ecological concerns, good pine nuts are crazy expensive. And if you buy cheap ones imported from China, there’s a chance you will develop the dreaded “pine nut mouth,” a condition that makes everything taste awful for a week or more.

In any case, there are plenty of nutty alternatives. Whether or not traditionalists will scold you for calling it “pesto,” you can make it with walnuts, hazelnuts, pistachios, almonds, pecans and, yes, pumpkin seeds. With the alternative nuts, just make sure you allow time to toast or blanch, and then cool, before using them in pesto.

Besides the nuts, I assert that you can and should experiment with the other components, including the basil and the cheese. Panizza describes pesto as “a garlic sauce aromatized by the basil.” Given that logical explanation, there’s no reason why one can’t aromatize the garlic with lots of different greens. I’ve made great pestos with Swiss chard, mint, parsley, dandelion and kale.

Many of us also still think narrowly when it comes to the cheese (always Italian, usually Parmesan or pecorino), but just about any hard, aged cheese theoretically could work, including Dutch Gouda, Spanish manchego and some artisan domestic renditions.

I’ve also done a little experimenting with different oils, using grapeseed and even avocado oil with some interesting results. For now, however, I mainly use the traditional olive oil. Good garlic and good sea salt are non-negotiable.

As for technique, I must confess that even though I have a beautiful mortar and pestle that I brought home from Genoa, I rarely use it. Prime grinding technique is tricky to master. So most of the time, like most home cooks, I use a food processor. I will say, however, that when I take the time to do it with the mortar and pestle, the results are richer, more velvety, and wonderful.

Rigatoni With Swiss Chard Hazelnut Pesto. (Deb Lindsey/For The Washington Post)

Beyond the mortar and pestle, Panizza insists there is no real secret. “Its all about experience and sensibility,” he says. “Then it’s a question of grams and sequence.”

Panizza’s sequence is first to mash the garlic and pine nuts with a generous pinch of salt, then to add the basil, grinding until it begins to bleed green liquid, at which point he adds the cheese and then drizzles in the oil. That order works well with the mortar-and-pestle method. But for the food processor, I like to start with the greens, followed by the garlic and salt, followed by nuts, then the cheese, and finally the drizzled oil.

Near the end of our lunch, after we finish the testaroli and move on to perfect pesto-enveloped trofie, I finally unburden my conscience and tell Panizza that I mostly use a food processor at home. He sighs and says that even in Italy, this is the modern reality. “These days,” he says, “a lot of Italian families still have the mortar and pestle. But they put a plant in it!”

Suddenly, I feel a little better about my arugula-pumpkin-seed-Gouda pesto.

(The Washington Post)

Wilson is author of the new Kindle Single “Spaghetti on the Wall.”