IIRC, property owners have up to 12 hours after a snowfall to clear snow and ice from the sidewalks adjacent to their property. Here's the city link
http://www.toronto.ca/transportation/snow/sidewalks.htm
So, if it snowed less than 12 hours prior, your SOL. Also, if the ice you slipped on isn't a result of snow that fell in the last 12 or more hours, but is due to melting run-off from adjacent snow piles, likely from the last time the property owner shoveled, you're also SOL, since the property owner can rightfully claim that he did clear the snow and ice within 12 hours after the snowfall, as required legally, but that melting run-off refroze, not due to snowfall, but due to warmer temperatures. The city bylaw says you must clear the ice and snow after a snowfall, not after a thaw and freeze of existing snow.
Lastly, you must remember, that it is the city, not the property owner who is ultimately responsible for clearing the snow and ice. Thus, if the property owner refuses, the city can fine the owner for not adhering to the by-law, but the city is responsible for providing public infrastructure, including sidewalks, so it is the city of Toronto that you must sue. See details at
http://www.theglobeandmail.com/servlet/story/LAC.20080215.SLIPS15//TPStory/National "Municipalities can fine homeowners for not clearing the snow in front of their homes, but the municipality will still be on the hook for any damages in a lawsuit"