It varies a lot since there's no one true recipe, but the three variations I've had were all pretty good in different ways. One was basically just a niçoise salad with minimal difference, another used a lot of edible flowers and some walnuts and was a bit lighter on the fish while using chorizo and cabanossi for the meat (liked this one the best), the other was by far the richest and used plenty of game, then went heavy on asparagus and roast veggies.
I would say that any recipe you find that doesn't have lemon or lime juice in the dressing is doing the thing a disservice, unless it has a fancy vinegar to replace it. It needs the acid to cut through the rich/oily aspects.