Montreal's Chinese population is only a fraction of the GTA's — I think roughly 150,000 vs 700,000 — so obviously there won't be as much of a concentration as in Toronto. But Brossard serves the same role as Markham and lately there has been an exodus of established places from Chinatown/downtown to the South Shore.
But it's not just Chinatown and Brossard. Shaughnessy Village (west end of downtown near Concordia) has had a large Asian population for at least 25 years now and while it's not growing as much as before, it's still pretty dominant, and in fact it has supplanted Chinatown as the main destination for Chinese food and groceries in the downtown area. (There's also a lot of Korean places around there, as well as location of H Mart, the Korean grocery chain.)
Beyond that, there's a pretty sizeable Chinese community in Ville Saint-Laurent/Cartierville (hence the first T&T location there), on the West Island and in LaSalle. Also, a lot of the Chinese people in Montreal are from Southeast Asia, so there's a certain Chinese-Vietnamese and Chinese-Cambodian presence in Villeray/Saint-Michel too. There's a cluster of Chinese-Vietnamese businesses at Jean-Talon/St-Denis, for instance, and there's a particularly big Kim Phat supermarket on Jarry East.
Based on the 2001 census, these are the (very rough) concentrations of Chinese people in Montreal, with the range depending on the census tract:
- Chinatown: 20-70% Chinese
- Brossard south of boul. Napoléon: 25-50% Chinese
- LaSalle near Angrignon metro: 20-55% Chinese
- Shaughnessy Village: 20-33% Chinese
- Cartierville around Marlborough Park: 20-43% Chinese
- Vieux-Saint-Laurent: 15-20% Chinese
LaSalle is the one most people would be surprised about, but numerically speaking it's one of the biggest Chinese population centres in Greater Montreal. It's pretty low-key but there are a number of Chinese supermarkets, though only a handful of restaurants.