2h20 isn't enough time to leave the airport and come back.

In the airport, there are several options for poutine, including St-Hubert (public area pre-security), Avenue des Canadiens pub (Domestic terminal), Archibald (Int'l terminal), Lester's (US terminal), Hurley's (US terminal), and a few others.

However, I don't think any of them have a vegetarian poutine option; the airport restaurants are all serving limited menus so you won't have a lot of choice.

If you do make it into Montreal on a future trip with more time to spare, here are some great options for veggie poutine: http://www.tourisme-montreal.org/blo...y-in-montreal/