Method

1. In a small pot, combine the apple cider vinegar, white vinegar, honey or maple syrup and heat until hot, but not simmering or boiling, and the sweetener has completely dissolved.
2. Next, add the sliced red onion to the vinegar mixture. Press the onions down with the back of a spoon until they are completely submerged in the vinegar mixture. Let the onions sit until they begin to turn a bright pink, purple color.
3. Remove the pot of onions from the heat and let them come to a complete cool. Once the onions are room temperature, transfer them to a storage container and store in the fridge.