I wish you the best of luck with that and hope you get some good answers. I was on a similar quest, a few years ago, and found next to nothing. Most places make either a Niçoise that not a Niçoise at all or they serve you some overpriced "seared tuna" BS.
Ah, now you've got me craving Niçoise and pissaladière.
Lemeac circa 2008
Le Cartet circa 2008
Le Cartet circa 2009
Le Local circa 2008
Ariel circa 2011
Horribly overpriced bad food. A bit of a tourist trap. However, the (16$) hamburger is pretty good; but obviously not worth the price. There is a reason it is often almost empty when nearby restaurants (even more expensive ones) are completely full.
To be avoided in my opinion..
Moules frites is the easiest dish to make so yeah, I should hope its good.