Sprinkle some of the lemon juice over the chopped onions: Sprinkle the lemon while you prepare the other ingredients. This will take some of the oniony edge off the onions.
Combine the ingredients in a bowl: Drain the oil from the tuna and put the tuna into a large bowl. Add the beans to the tuna and gently stir to combine. Add the onions, herbs, black pepper, lemon zest and lemon juice and mix to combine. Add Tabasco or chili to taste. If the salad needs more acid, add a little more lemon juice. If the salad seems a little dry, add a little bit of extra virgin olive oil. Add salt to taste.
Chill before serving: This salad will last several days in the fridge, tightly covered.
