SERVES 4
This classic dish comes from the section of Spain’s Atlantic coast that slopes toward the Strait of Gibraltar. There, the schools of tuna that migrate each spring into the Mediterranean to spawn are funneled past the fishing towns of Conil de la Frontera, Barbate, and the wonderfully named Zahara de los Atunes (Zahara of the Tunas) that still catch atún rojo de almadraba—trap-netted bluefin tuna—following ancient methods.
While there is no single recipe for this dish, the variations tend to be slight—some cooks add parsley and nutmeg and leave out the oregano, others use aged vinegar instead of white wine or sherry. Without a doubt, the finest version I’ve had was at El Campero, José Melero’s restaurant in Barbate. Instead of the fino sherry, José uses some twenty-five-year-old sherry vinegar, and chooses fat-marbled mormo, a hard (if not impossible) cut to buy, from the top of the head at the neck of the tuna. Use a cut with a bit of fat—like ventresca, the belly—which will keep it moister. It makes an exquisite tapa.
1. In a cazuela, heavy casserole, Dutch oven, large sauté pan, or deep skillet, heat the olive oil over medium heat. Add the garlic and cook, stirring frequently, until fragrant, about 1 minute. Add the onions, season with salt, and cook over medium heat for 5 minutes, until they begin to soften and turn pale. Reduce the heat to low, cover the pan, and cook, stirring from time to time, until the onions are tender and translucent, about 40 minutes.
2. Add the oregano, paprika, and ¼ cup/60 ml water. Sprinkle in the flour and stir until it is dissolved. Arrange the tuna in the pan, add the bay leaf, and drizzle over the sherry. Simmer uncovered over low heat, until the tuna is just warmed through and still a touch purple in the very center, about 5 minutes. The sauce should be thickish and the onions meltingly smooth. Taste for seasoning and adjust as needed. Remove from the heat and let cool for a few minutes before serving.