Where to eat between Toronto airport and Waterloo?
Not really, apart from some economical Indian restaurants (Brar Sweets on Advance Blvd, as well as some others) that are a few km nw of the airport. Not sure if they'd be open early Sunday evening.
As far as I know (I drive that stretch fairly often), there are no interesting restaurants to eat along the way to Waterloo that are relatively convenient to the highway. The only rest stop on the way to Waterloo via the 401 is closed for renovations right now, so if you decide to stop, you'll have to choose an exit and drive a km or 2. Most of the Mississauga and Milton exits have a variety of chain restaurants and gas stations fairly close to the exit ramp.
Brar Sweets & Restaurant
199 Advance Blvd, Brampton, OH L6T4N2, CA
Zet Drive-Inn Restaurant
6445 Airport Rd, Mississauga, ON L4V1E4, CA
If you get off on the Mississauga Road exit on the 401, you can go to Ming Room, a Hakka Chinese restaurant. I only went there once this past September as I heard many positive reviews, and it was really good. A good twist on the traditional Chinese and Indian dishes.
We tried several dishes together but my favourites were the paneer and fried rice dishes. They are open on Sunday nights too.
6461 Mississauga Rd, Mississauga, ON L5N1A6, CA