In a small saucepot, bring the white wine vinegar, sugar, salt, chili pepper and bay leaves to a simmer over low heat. Put the sliced red onions in a small sealable container. Carefully pour the hot liquid over the onions, cover and give it a shake. You may need to lift the lid to release some of the pressure. Every now and then, give it a good shake. Refrigerate to cool.
Recipe courtesy of Rachael Ray