1 red onion; thinly sliced
1 cup water
1/4 cup white vinegar
1/4 cup apple cider
2 tbsp sugar
1 tbsp peppercorns
2 tsp salt

1. Place onions in a jar.

2. Whisk the liquids with the sugar and salt until dissolved. Add peppercorns.

3. Pour over onions, refrigerate a few hours.

Notes:
You can also boil the liquid mixture then pour over the onions if you want them to have a little less bite.

Keeps about 2 weeks.