I'm new to this site and I've got a question for you guys. Every now and then, in different recipes that call for raw or sauteed onion, I find that the onion goes bad and gives off a kind of rancid flavor. For instance, I made a red cabbage slaw last night with red onion in it. When it was fresh, it tasted delicious. After sitting for some time (on my stovetop, while something was baking), the onion gave off a really gross flavor. I've noticed it in a potato salad recipe that I make, that calls for raw onion. Its delicious when it's fresh but once it sits in the fridge overnight, the onion suddenly tastes awful. This is also the case with sauteed onions. There is one recipe I make with breaded fried eggplant, sauteed onions and green peppers. For some reason, when I add the onions to the eggplant, and heat it up with tomato sauce, suddenly the onion tastes terrible. Ive searched online for some info on this, but found absolutely nothing. Am I crazy? Thoughts, anyone?