I have been to many vietnamese restaurants in Toronto including the "popular" Golden Turtle on Ossington, and this place is by far my favourite! Owned by a Vietnamese family, the restaurant is authentic, delicious and cheap! The outside of the building is a little basic and you may not even think to go in, however the food and friendly service are sure wins.
Ask for the veggie salad rolls (not on menu) - they are amazing!
Note that it is closed on Tuesdays!