“Pronounced ‘pahn-bahn-yah,’ the ingredients in this Niçoise-style sandwich are a good match for soft, crusty ciabatta bread, but a French baguette that is not dense and chewy will do the trick too. Use good- quality tuna packed in oil, not water, or sub in chunks of freshly grilled tuna. This is, for the most part, a classic make-ahead sandwich—traditionally, it is allowed time to marinate before serving—but if you’re hungry and can’t wait, it’s just as delicious served straightaway.’
In a food processor, combine the aioli, crème fraiche, basil and half the lemon zest and juice, and process for about 20 seconds, or until the basil is coarsely chopped but not puréed. Season the basil mayonnaise to taste with salt and pepper.
In a small bowl, gently fold the tuna, olives, capers and the remaining lemon zest and juice to combine, keeping the tuna in large chunks as much as possible.