It’s actually a pretty traditional salad - Salade Niçoise or insalata nizzard, although you dress it with a vinaigrette. Here’s one.
I had an absolute beauty while on holiday a few months ago. It was all the standard stuff piled on a plate. With capers and mustard seeds mixed through the salad. The fish was grilled and placed atop as a whole fillet and instead of hard boiled eggs a poached egg sat on top of it all. On the side was a small pot of aïoli.
Tuna salad is the one thing I still use Miracle Whip instead of mayonnaise to make. The zip kinda tastes like the sweet relish, which I can never justify buying for it’s limit use. If I make a sandwich, and I have some, I’ll add lettuce and/or bell peppers.
I do also make a mayo version–but it also involves apples and grapes. It’s essentially a chicken salad (ala Arby’s) with tuna. And it usually gets added to noodles, rather than made into a sandwich.