Think of this fabulous Catalan dish as Spanish sashimi or Spanish carpaccio. The really neat and surprising thing, however, is that the raw flesh of choice is salt cod! You'll be delighted at how deliciously it blends with the traditional tomatoes, onions, red-wine vinegar, and olive oil. About the latter: make sure to use only the greatest, youngest extra-virgin Spanish olive oil you can find; we recommend Nuñez de Prado from Andalusia. About the salt cod: make sure to use the highest-quality, thickest, moistest salt cod you can find. We sell a terrific piece at the store that needs only 24 hours of soaking; if yours is saltier and drier, you might want to soak it for 48 hours. We have tweaked the tradition of this dish by adding the sweetness of roasted red peppers to it; you may leave them out if you wish a more austere creation. Either way, it's a great liftoff for a Spanish dinner party. Serves 6 as a small first course.