The closest thing in the Highway Traffic Act that deals with hand position would be the distracting driving law (eg: just the act of holding a cell phone). It doesn't apply here, but it's the closest thing. Now if I replace the cell phone with a sandwich, it's no longer distracted driving because it's not an electronic device.
Depending on the right circumstances, (eg: vehicle is moving, eating a sandwich, emergency arises, unable to perform quick maneuver, and then an accident) there's a good chance you'll be charged with careless driving. Holding a sandwich instead of the wheel would be considered careless. So would not holding the wheel at all, but it's probably easier for me to use an everyday example. If the circumstances end up being more serious (accident involving death), you can probably be charged criminally.
Now if you're at a red light, i'm not sure how likely you are to be charged with anything. Since careless driving is a blanket charge and one not directly covering the idea of hand positioning, you'd have to prove the act of carelessness. Maybe i've missed something and someone else could chime in.