In a sauce pan over medium heat combine apple cider vinegar, white balsamic vinegar, water, sugar, salt, juniper berries, ground anise and pickling spice. Stir to combine.
Bring to a boil and remove from heat. Once cooled place onions in quart canning jar and then add liquid until filled.
Store in fridge for 2 weeks.
Recipe by Dining with Alice at https://diningwithalice.com/appetizers/pickled-onions/