PoutineVille is one of my favourite restaurants in Montreal (I can expand that range to all of Canada now that they have a Toronto location as well ;-) ).
I highly recommend the "patates écrasées" (which they translate as "crushed potatoes" but I've always thought sounded better as "smashed potatoes", not that I'm taking credit - that was actually put forward by a review in the now-defunct Montreal Mirror). Since I really prefer sweet potatoes, that's what I often order nowadays, also delectable.
You should definitely try the red wine sauce, and feel free to ask for a sampler of their different sauces. All sauces except the meat sauce are vegetarian.
The pictures I took were at this location, but the review applies to the Beaubien restaurant as well. I'll be seeing you guys again soon to get my fix :-).