1 ½ pounds fresh albacore or yellowfin tuna, cut into 1 ½-inch thick pieces
2 ½ cups olive oil
4 garlic cloves, peeled
1 dried red pepper
2 bay leaves
2 (1-inch) strips lemon zest
1 teaspoon black peppercorns
FOR THE PICKLED ONIONS
1 red onion, thinly sliced
2 tablespoons red wine vinegar
FOR THE MAYO
1 teaspoon kosher salt
1 tablespoon fresh lemon juice
2 garlic cloves, mashed into a paste
2 large egg yolks
1 cup|250 ml canola oil
FOR THE TAPENADE
⅓ cup|40 grams pitted castelvetrano olives, finely chopped
¼ cup|40 grams pitted nicoise olives, finely chopped
1 tablespoon capers, finely chopped
FOR THE SANDWICH
1 baguette, halved lengthwise
3 Persian cucumbers, thinly sliced
Kosher salt, to taste
3 tomatoes, thinly sliced
1 bunch fresh basil, leaves picked and thinly sliced
- Confit the tuna: Season the tuna with salt about 30 minutes before you plan to cook it.
- Place the oil, garlic, red pepper, bay leaves lemon zest, and peppercorns in a Dutch oven or deep heavy saucepan. Heat to about 180°F; the oil should be warm to the touch, but not hot. Cook for about 15 minutes to infuse the oil with the aromatics and also to pasteurize everything to allow for a long shelf life.
- Slip the tuna into the warm oil in a single layer. The tuna must be covered by oil, so add more if needed. You can also cook the fish in batches if necessary. Return the oil to about 150°F, or just until you see the fish emitting a bubble or two every few seconds. The precise temperature of the oil isn’t so important, and it will fluctuate as you turn the flame up and down and add and remove the fish. The important thing is to cook the fish slowly, so err on the low side if needed. After about 9 minutes, remove a piece from the oil and check for doneness. The fish should be barely medium-rare; still quite pink in the center, as heat will continue to carry over. If it’s too rare, return the fish to the oil and cook for another minute.
- Remove the cooked fish from the oil and allow to cool on a plate in a single layer, then place in a glass container and strain the cooled oil back over the fish. Serve at room temperature or chilled. The fish will keep in the fridge, covered in oil, for about 2 weeks.
- Pickle the onion: Place the onion in a large bowl and cover with the vinegar. Set aside for 15 minutes.
- Make the mayo: Dissolve the salt in the lemon juice in a medium bowl. Add the garlic and egg yolks and whisk to combine. Slowly add the canola oil, whisking constantly, until emulsified. Cover and refrigerate until ready to use.
- Make the tapenade: Mix all the ingredients in a bowl and set aside.
- Assemble the sandwich: In a large bowl toss the cucumbers with 1/2 teaspoon salt and let sit for 5 minutes.
- Remove the tuna from the oil (save the oil! You can reuse it! And we will use it again in this recipe! Just wait!). Flake the tuna into the bowl with the cucumbers, then add the tapenade and ⅔ of the mayo. Add half of the onion and half of the basil and season with salt and pepper.
- Spread the remaining mayonnaise on the inside of one side of the baguette. Brush the other half with some of the tuna oil. Top the bottom half of the bread with the tomatoes and the tuna mixture, then the remaining onions and basil. Slice and serve.