When a friend came for an impromptu dinner one summer evening, I came up with this Mediterranean-style salad. We scooped it up in lettuce leaves and corn tortillas for a casual supper on my patio.
Cut the fennel bulbs lengthwise into quarters, cut out the core and then slice crosswise. In a large bowl, combine the fennel, beans, tuna, onion, olives, and mint.
In a small bowl, place the mustard. Whisk in the lemon juice. Gradually whisk in the oil and a generous amount of pepper. Gently mix into the salad. Season to taste with salt and pepper.