Best breakfast option I could find at 6am in Terminal 3 at YYZ. Egg & Cheese Panini on your choice of bread or bagel. $6.77.
Toast of Toronto also offers toasted bagels with cream cheese and a bunch of to go cold items like salads, various sandwiches, cold bagels with real cheddar cheese, breakfast pastries, yogurt etc.
Their cold beverage case offers my number one airport necessity - sparkling water & it looks like they turn into more of a deli and bar as the day goes on.
Excellent service.