I was in the middle of making spaghetti sauce the other day, when I got interrupted. I had already put fresh onions and garlic in the crockpot and then I poured fresh tomatoes on top, but hadn't stirred them in yet. When I returned an hour later, the onions had turned TURQUOISE! They tasted just fine. I am guessing it was a chemical reaction, but can't find any info about it. Does anyone know what this is?