Quick Pickled Red Onions

Bahan-bahan (2 porsi)

• 1 large red onion, peeled and very thinly sliced*
• 3/4 cup apple cider vinegar
• 1/4 cup water
• 1 teaspoon fine sea salt
• 1 -2 tablespoons sweetener (such as maple syrup, honey, sugar, etc.)