Ingredients:

  • 1 medium red onion, thinly sliced (approx. 8 oz / 225g)
  • 1/2 cup apple cider vinegar
  • 1/2 cup warm water
  • 1 tbsp granulated sugar
  • 1 1/2 tsp kosher salt

Instructions:

  1. Thinly slice the red onion into half-moons, approximately 1/8th of an inch thick, and pack them tightly into a clean 16 oz glass mason jar.
  2. In a small saucepan, combine apple cider vinegar, warm water, granulated sugar, and kosher salt.
  3. Place the saucepan over medium heat for 2–3 minutes, stirring constantly until the sugar and salt have completely dissolved.
  4. Pour the warm brine directly over the sliced onions in the jar.
  5. Use a spoon to press the onions down to ensure they are fully submerged, seal the lid, and let sit at room temperature for at least 30 minutes.