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Editor's Note: We're very excited to welcome writer, photographer, and cook Michael Harlan Turkell to the virtual pages of Serious Eats. In this series, Michael will share some of his favorite takes on grilling recipes from around the world, all focused on the interplay of vinegar and the grill—something he knows quite a bit about, as he traveled far and wide while writing his awesome vinegar-focused cookbook, Acid Trip (coming out in August 2017). You can preorder the book here.
I started developing this recipe with a specific vinegar in mind: sherry vinegar. Sherry vinegar is made from fortified wine in the Cádiz province of Spain, mainly in the city of Jerez, which is known as the sherry capital of the world. It has a tangy oxidized note that nicely complements grilled food. Its distinct flavor comes from the method by which the sherry is made. Using what is called a solera system, barrels are stacked in a multi-level pyramid structure. New wine goes in the top barrels, and is gradually blended downward into the older barrels. The finished product becomes a blend of ages, rather than a single vintage. The same system is employed to age the vinegar, with the younger barrels picking up complexity from the older vinegars and the newer ones adding freshness to the older ones. The result is nuanced and singular. While some vinegars can be too assertive, sherry vinegar is mellower and has a roundness due to its significant aging, but it also isn't syrupy like balsamic.
I went searching for a sherry vinegar–based sauce that would make sense for grilled foods. In my online quest, I came across a little jar from a Spanish company called Ferrer. The label read: "Xató Salsa." I started Googling around—what was xató? At first glance, it certainly seemed romesco-like, if not simply just romesco—a combination of nuts, tomatoes, peppers, garlic, and sherry vinegar. But I noticed that Ferrer was selling both jarred xató sauce and romesco. Was this just a marketing ploy? I went deeper.
I found that in Spain's northeastern region of Catalonia, the towns of Canyelles, Calafell, Cubelles, Cunit, El Vendrell, Sant Pere de Ribes, Sitges, and Vilanova i la Geltrú are considered the "xató route." There, a salad comprised of endive or frisée, bacalao (salt cod), oil-packed tuna, and anchovies is topped with a nutty, sweet, and slightly spicy condiment. Each town has its own iteration of the salad, some with different fish, some with olives, some with toasted nuts as a garnish. In those towns, this salad is called xató. In the nearby town of Valls (still in Catalonia), a sauce with a different name, salvitxada, is used to top calçots (spring onions) during the Calçotada festival. In the months leading up to spring, long deeply-rooted onions are harvested and grilled over a hot fire until they're black, at which point they're wrapped in newspapers to steam. Their charred exteriors are then peeled off with bare hands, and the soft onions are dipped in romesco, ahem, "salvitxada."
To make any of these sauces, the process is the same: Dried spicy red peppers are reheated in warm water and blended into a smooth paste with nuts, tomato, a clove of garlic, sherry vinegar, and olive oil, thinned in both flavor and consistency with water, then thickened with grilled bread.
I wanted to see if I could intensify all of these enchanting elements on the grill. I blistered fresh Fresno peppers to skip a dried-pepper soaking step. Most romescos are made from ñora peppers; they're small, red, round, and sweet-fleshed and almost always used dry. They can be hard to find whole and dried in the States (though online sources exist). Roasting fresh peppers on the grill creates a smoky depth not unlike a dried pepper, so it's a substitution that works well.
I also charred a tomato and toasted foil packets of nuts over the coals. The resulting flavor of the sauce almost reminded me of Spanish chorizo sausages, a bit peppery and smoky. With the addition of sherry vinegar to the mix, it was light and bright and could certainly be used for fresh vegetables or a salad.
Following the traditional way of serving xató, I reached for endives first. I love grilling them—it tames their natural bitterness—and I put some spring onions over the coals, too, a holler at Calçotada. While I omitted most of the cured seafood that you'd find on the xató route, I did top the salad with anchovies for a little briny seasoning. You can easily add flaked salt cod, oil-packed tuna, or even a rare seared tuna steak on top to make for a great main course salad.
One thing about xató continued to confuse me though. The more and more I looked into it, the more it seemed like "xató" refers to the entire salad, not just the sauce I'd found in a jar. I asked my friend Alex Raij, the chef and owner of NYC's Txikito (her tribute to Basque country cuisine) and several other Spanish-inspired restaurants, about xató sauce, and she was adamant that the name refers only to the the iconic salad. She figured that the jars I'd seen with "xató" on the label were nothing more than micro-regional marketing. But I still couldn't get that jar of bright orange goodness out of my mind. When I bumped into Alex's husband, Eder Montero, a Basque-native, I asked him about xató sauce, too. He was just as confused and resolute as Alex had been. He even texted a friend in Spain who formerly cooked for legendary chef Ferran Adria to see if he'd ever heard of such a thing. His friend's response was this: Xató must have more pepper, and fewer nuts, but it sounded basically the same as romesco. Apparently, there are many different sides to romesco; it's just a matter of where it comes from.
Whatever the case, I was happy with this tangle of char and acidity that I'd created—not quite the definition of xató, but unquestionably a celebration of the vibrant condiment I've come to love. This sauce is a route worth following.