I don't know enough about Alfred Dreyfus the man to know whether or not he kept kosher. I sort of doubt it, since he was in the 19th century French army, where bringing a sack lunch was probably not an option. But while making salad niçoise for dinner just now, I noticed that, of all complicated, classically French dishes, it's the only one I can think of that, even if prepared with all the traditional ingredients, is 100% kosher. (I'm not including things like roast chicken, which could either be or not be kosher, but which are too simple to count in either direction.) Unlike steak frites, which would be kosher except that butter's usually involved, salad niçoise is just fish, vegetables, and eggs. Most cheeses are not kosher, which eliminates dishes with cheese as an ingredient. I tried to find the history of the salad online just now, but found only a bunch of recipes (including one for a crab salad niçoise, which wouldn't so much count) and this lack-of-wikipedia-entry. Does anyone know the history of salad niçoise? I'd like to think I'm on to something.