Everyone seems to have a very strong opinion as to what should or should not go into a Salade Nicoise, my recipe is a guide and what I think makes a really good Nicoise. If you don't have some of the ingredients just use what you have in the fridge / store cupboard but I do think the quality of a salad like this is completely dependent on the quality of the ingredients. Try to get good quality free range eggs, wonderfully ripe tomatoes (IOW tomatoes are great - if you don't have good tomatoes use sun blush tomatoes), non-pareil capers (non-pareil means has no equal in French so they are the best), the best olives and the best anchovies and tuna you can lay your hands on (my favourite are Ortiz). Do use your best peppery olive oil for the dressing, I use Fino from Spain which I love and sell if you want any.
Capers are sold by size so the smaller the caper the more delicate the texture and flavour are. So non-pareil capers are the smallest you can get so should be by definition the best and if the jar does not say non-pareil then the capers will be a little tougher, larger and not as delicate. If you can get them salted rather than in brine even better, soak them, wash them off and then use them.
Re the tuna, fresh tuna is lovely but it is expensive and tinned / jarred is just as good here. I absolutely adore Ortiz tuna in oil. I think Spanish seafood experts Ortiz make the best canned tuna available to buy in the UK. They also only fish at the point in the season when the tuna weigh 30kg or less, to give the most tender fillets. All the fish that Ortiz buys is caught on rod and line in the Bay of Biscay and then processed by hand and is ethically sourced. I buy Ortiz tuna and anchovies online - Brindisa (www.brindisa.com) are a great source of Spanish foods and have some wonderful tinned fish as well as paprika, manchego and Iberico hams (also try the Sobrasada - it is incredible!).
Potatoes are not really authentic but I like adding them (waxy new potatoes or Jersey Royals when in season) as they add bulk and I am feeding a hungry family of men who balk when I say we have salad for lunch! If you are time short to boil potatoes and let them cool then add good quality baked croutons from a packet.