1. If you don’t have prepared pesto on hand, first mix the olive oil with the basil in a blender or food processor. Drain and rinse the beans. Drain the tuna.

2. Combine the lemon juice with the pesto in a mixing bowl, then add the beans and tuna.

3. Quarter the tomatoes, spoon out the seeds, and finely chop the flesh. Add the tomatoes to the bowl. Toss the ingredients together and season to taste with salt and pepper.

4. Rinse the watercress. Chop the watercress leaves into the salad or serve the salad over sprigs of watercress.

Variation

My friend Dana Jacobi, food writer, consultant, and connoisseur, suggested a delicious combination of white beans with smoked tuna fish. With the few changes outlined below, the above salad accommodates the smoked fish rather nicely.

Omit the pesto. Finely mince 1 shallot, 2 scallions (green onions), or a bunch of fresh chives. Also mince ½ cup fresh parsley leaves. Dice 1 pound smoked tuna. Combine ¼ cup olive oil and ¼ cup lemon juice and add the minced shallot, scallions or chives, and parsley. Add the drained beans, smoked tuna, and tomatoes. Toss well, season, and serve over watercress.