Prepare the dressing base: In a small jar or bowl, combine the lemon juice, extra virgin olive oil, Dijon mustard, minced garlic, salt, and black pepper. Screw the lid on tightly and shake vigorously for about 15 seconds, until the dressing looks pale yellow and slightly emulsified. You should see no separation of oil and lemon juice — it should appear creamy and uniform.

Build the salad foundation: Place the drained tuna in a large salad bowl. Using a fork, break the tuna into flakes of even size — you want some larger chunks for texture, but no pieces larger than a thumbnail. The tuna should look light and flaky, not mushy or overly shredded.

Add the beans and vegetables: Add the rinsed cannellini beans, finely diced red onion, and diced celery to the bowl with the tuna. Toss gently with your hands or a fork to combine. The beans should remain mostly whole, with some breaking apart naturally — this is fine, as it adds creaminess. The onion and celery should be evenly distributed throughout the mixture.

Fold in the fresh herbs: Sprinkle the chopped parsley, dill, and thyme leaves over the tuna mixture. Use a spatula or salad servers to fold everything together gently. You should see flecks of green throughout the salad, and the herbs should release a bright, fresh aroma as you work them in. If using capers, add them now and fold gently.

Dress the salad: Pour the lemon herb dressing over the salad. Using the salad servers, fold the dressing through the mixture in a gentle lifting motion, turning the salad from the bottom to the top. Continue for about 30 seconds, until every flake of tuna and every bean is lightly coated. The salad should look glossy but not wet, and you should smell the lemon and herbs clearly.

Rest and serve: Let the salad sit at room temperature for 5 minutes before serving. This resting time allows the beans to absorb some of the dressing and the flavours to meld together. When you taste it, the lemon should be bright but not sharp, and the herbs should taste fresh and present. Serve immediately, or cover and refrigerate for up to 24 hours.