Keto Pickled Red Onions

1. Slice the red onion as thin as you can, using a mandoline if available. 
2. Stuff all the thinly sliced red onions into a jar of your choice, or use a bowl. 
3. In a measuring cup, combine the apple cider vinegar, white vinegar, salt, sweetener, and warm water. Stir until the sweetener and salt are fully dissolved. 
4. Pour this pickling mixture over your sliced onions and let them set for at least an hour at room temperature. 
5. After an hour, cover the jar and store the pickled onions in the fridge for up to three weeks. Enjoy!