Real Restaurants in Montreal?
Well, as we get 15-25cm of snow (up to a foot), local fruits and veggies are somewhat lacking. The chef at Le Peid Du Cochon is reputed to hunt some of the game he serves, and he does very interesting stuff (some of which works, some not) with foie gras.
You'll also want to visit fromages Chaput on Bernard St. West. See Carswell's post on them, below. Fromagerie Hormel is also a treat; they age a lot of cheese, some with added local beers.
The last local product to sample would be ice ciders; made from apples left to freeze in the orchard, its similar to ice wine in its sugar and complexity.
Although it isn't a "hidden gem", Toque's formula is to prepare dishes from the best available local products. I've only been once and the waiter introduced several dishes in detail, including from which local organic farm main ingredients were sourced. You may want to give it a shot...and make sure to reserve ahead.