I went to Plein Sud twice during the last month which might give you an idea about how much I liked it the first time I went there. It's situated in the Plateau-Mont Royal neighborhood, at a walking distance from the Mont Royal metro station.
Their Table d'hote for lunch comprises of a soup/salad, a main dish and a dessert. I opted for the cold soup which was excellent. It was more like a vegetable smoothie (albeit less viscous) than a soup but excellent nonetheless. The Onglet de Boeuf that I ordered was done to perfection and the petit choux dessert was very good as well.
We liked their cooking so much that we decided to go there once more to check out their famous Magret de Canard. They had cooked it in a Fig sauce with a gratin and a salad on the side. It was exceptionally good. The dinner Table d'hote doesn't have a dessert included, so you'll have to pay extra for if you need any. We opted for the crème brulée and found to our liking.
The dinner can hit your pocket hard if you add wine and dessert to your meal and you might end up paying approximately $50/person. But this isn't meant to be a criticism, it's only a heads-up to fellow Yelpers.
All in all a very good experience. I'd recommend this restaurant to my friends/family.
Table d'hote lunch: $15-18
Table d'hote dinner: $25-30