1/2 cup distilled white vinegar (or ACV or a combo of both)
1/2 cup filtered water
1 tsp pink salt or sea salt
1 small red onion, very thinly sliced
Optional: 1-3 tsp coconut sugar, maple syrup, date syrup, or honey (I would personally opt for coconut sugar!)
Find it online: https://homecookedliving.com/how-to-make-pickled-red-onions/