Originally Posted by
true4uca
[QdoUOTE=quiltingcandy;7671525]I doubt that an onion would cause a problem - there are eggs and oil in mayonnaise which is much more likely to go bad if it gets warm. There are preservatives in mayo.
Does this mean when I use only half an onion I don!t need to toss the other half. That's what I always do as I only buy those white onions and around here those are at least baseball sized.[/QUOTE]
I use white onions as well. When I've used what I need for a recipe I will often dice it pretty small, put in baggie, flatten and freeze. This way I always have diced onions to use in cooking. I also will put half the onion in a square of plastic wrap, pull up the corners twist and make sure it's sealed pretty well, then into the fridge. I've never gotten sick from either onions or potato salad. I use Miracle Whip for the most part for my dishes so I don't worry.