Place all ingredients except onions into sauce pot over medium high heat. Bring just to a boil while stirring often.
While cider is coming to a boil, peel onions and slice into rings. Separate each ring.
When mixture comes to a boil remove from heat and add in onions. Stir and allow to sit for five minutes,or until onions have wilted down into vinegar some. Stir again and let sit for another five minutes.
Place in container, cover, and refrigerate until well chilled and ready to serve. Serve as a side relish or a topping on pinto beans, cornbread, etc.