I first tasted  aceto balsamico tradizionale when a friend from Modena arrived for dinner with a tiny bottle a quarter filled with a dark liquid. After cutting a chunk of Parmigiano-Reggiano  for each of us, he tilted the bottle above my plate. I waited, and waited, and waited. Finally, a few dark pearls emerged, hung on the bottle’s lip, and dripped ever so slowly onto the cheese.

“It’s worth waiting for,” he assured me. “It’s been aging for sixty years.” It was indeed worthy of anticipation. Rather than the acidic flavor I expected, the syrup tasted rich, smooth, velvety, soothing.

Years later, on a visit to Modena, I asked Davide Lonardi, a third-generation balsamic vinegar producer at the Acetaia Villa San Donnino, why this elixir doesn’t taste at all vinegary.

“There’s no vinegar in it,” he explained. “The only ingredient is mosto (must), or cooked grape juice.” The misleading name dates back to the Middle Ages, when apothecaries sold aceto as a treatment for everything from sore throats to fussy stomachs. Some claimed the tincture could even raise the dead—or, at least, revive victims of the plague.

The process, which has changed little over the centuries, begins with skinning and pressing local grapes—white Trebbiano, red Lambrusco, or a mixture of both. Then the vinegar maker cooks the remaining must very slowly in a vat for twenty-four hours, never letting it boil. Unlike wine, which comes to its fullness in carefully regulated conditions, true aceto balsamico matures in lofts and attics that are cold in winter, hot in summer, and damp during rainy seasons.

In the attic of his converted farmhouse, Davide displayed rows, called batterie, of five barrels, made of mulberry, cherry, or oak for different flavors, arranged from the largest at the top to the smallest at the bottom. The must mingles with a “mother,” or starter, from a previous season in the biggest barrel. As liquid evaporates, he replenishes the level in the smallest barrel from the next biggest one, repeating this process with every barrel—over and over again for a minimum of twelve years, although longer is better. A committee of experts, relying on their discerning palates in blind tastings, determine if the final product merits designation as an official aceto balsamico tradizionale di Modena.

The longest-aged bottles of this liquid gold cost more than rare cognacs. Yet the high price doesn’t cover the labor and time the arduous process demands. “That’s why passion is the most important ingredient,” says Davide. “The last vacation I took was five days in 1995. I have to be here, in my attic with my barrels, working from the heart. This is what makes it different from commercial products that just add flavorings to vinegar.”

At the end of our tour, we sampled traditional balsamic vinegars of various ages, relishing the richness that time imparts. Then Davide poured a thick aceto balsamico tradizionale, twenty-five years old, over a scoop of vanilla gelato. With no idea what to expect, I took a tentative lick. The combination of dark and light, tart and sweet, tepid and cold exploded in my mouth, and I almost laughed in surprised delight.

Davide grinned. “This is my passion—the emotion, the tradition coming together to give people a true flavor of Italy, something that can’t be found anywhere else in the world.”

Adapted from LA PASSIONE: How Italy Seduced the World.   Dianne Hales is also the author of LA BELLA LINGUA: My Love Affair with Italian, the World’s Most Enchanting Language and MONA LISA: A Life Discovered. For more information,  visit diannehales.com.