This salad should be made in the morning of the picnic. If you use a plastic box with a well-fitting lid, then it will survice unscathed until lunchtime - even a late lunchtime. Best kept in a cool-box or cool-bag.
Traditionally, Salad Nicoise is prepared with beans and tuna, and you could certainly use these ingredients. Even tinned tuna is possible. Personally, however, I like to include the beans but substitute tinned anchovies for the tuna - mainly because I usually have tinned anchovies in the cupboard at home.
First, hard-boil three or four eggs. Place the eggs in a saucepan with enough cold water to cover them. If possible, leave the eggs in the cold water for half an hour, giving the eggs a chance to warm up a bit. (They've probably been in the fridge.)
Then, bring the water to the boil, and boil for eight minutes. Drain off the hot water, and fill the saucepan with cold water. Cooling the eggs in this way prevents them from going black. Shell the eggs under running cold water and put back in cold water for ten minutes until cold.
If you are adding beans, use those long thin green beans. These need to be cooked before adding to the salad. Wash the beans, and cut off the "tops-and-tails". Put in a microwaveable dish, add a splash of olive oil and a pinch of salt, and just a little water. Microwave for about three minutes - they should still be firm to the teeth afterwards. Rince the beans in cold water and allow to cool.
In a plastic box, place any other salad items you fancy. I like a selection of crisp greens, finely-sliced radishes and spring onions, and chunked (not sliced) cucumber.
Over the top, place the drained beans and the boiled eggs, sliced into quarters. Open a tin of anchovies and drain off the oil. Separate the fish fillets and place one over each of the egg quarters. Keep as cool as possible.
Make up a portion of my Balsamic Salad Dressing. Keep the dressing in a separate container, and pour over the salad just before it is served at the picnic.