Instructions

1. Drain and rinse 2 (15-ounce) cans cannellini beans in a fine-mesh strainer. Drain 2 (5-ounce) cans oil-packed tuna into the strainer with the beans, but do not rinse.
2. Finely grate the zest of 1 medium lemon into a small bowl (about 1 tablespoon zest). Juice the zested lemon into the bowl (about 3 tablespoons juice). Add 1/4 cup basil pesto, 1 tablespoon olive oil, 1 teaspoon Dijon mustard, 1/4 teaspoon kosher salt, and several grinds black pepper. Whisk well to combine and emulsify. Taste and season with more salt as needed.
3. Trim the end, stalks and fronds off 1 small fennel bulb. Halve the bulb through the core, very thinly slice it crosswise, and place in a large bowl. Halve 1 small radicchio through the core, then cut the core from each piece. Slice crosswise into thin strips and add it to the bowl.
4. Add 2 ounces arugula (about 2 packed cups) to the bowl of radicchio. Drizzle with 2 tablespoons of the pesto vinaigrette and toss to coat. Spread the mixture out on a serving platter or divide among individual shallow bowls or plates.
5. Place the drained beans and tuna in the now-empty bowl (no need to wipe out). Drizzle with 2 tablespoons of the pesto vinaigrette and toss to coat. Spoon the mixture over the radicchio and arugula. Drizzle the remaining pesto vinaigrette over the top. Sprinkle with a generous pinch of flaky sea salt, if desired, and serve.