Craving a peanut-free burger experience without going the mega-chain route? You might want to check out Hero Certified Burgers. It's an upscale burger joint with 17 locations in the Toronto area. Burgers are 100% Canadian, range-fed, hormone and antibiotic free Angus beef; there's also vegetarian, chicken and salmon burgers available. While it looks like several of the sauces are manufactured on lines that also manufacture peanut and nut products, and should therefore be completely avoided, there are lots of other fresh toppings to pick from, including a great selection of cheeses.
According to the manager on duty at the King and Yonge location, grape seed oil is used for the deep fryer.
I'm going to email the company to see if there's any chance they can start offering some completely peanut-free sauces. Stay tuned.
Always do your own research.