Having sampled many many many salad niçoises both at home and in Paris, I can say without a doubt that American chefs have elevated this salad to a gastronmic height unachieved in Continental lands. Their substitution of seared tuna for plain-old canned fish provides a Gladwellian salad tipping point, and moves this humble dish of tuna, lettuce, beans, potatoes, eggs, and olives into the realm of culinary magnificence.