Why would you waste food by trimming the edges of the polenta? Maybe a fancy restaurant where every piece has to have perfectly cut edges would need to do this, but a home cook would never waste food like that. Hopefully the smart cook will use the trimmed pieces to make a nice little lunch for the next day! Two simple ways to use leftover polenta are to fry it with salsa and cheese on top or fry it and put honey on top. YUM!