275g red onion, thinly sliced
½ cup apple cider vinegar
1 tbsp fine white sugar
1 ½ tsp salt
1 cup hot water

1. Slice red onions as thin as possible. Transfer to mason jar.

2. In a measuring cup, combine apple cider vinegar, salt, sugar and water. Hot water helps the sugar to dissolve. Pour pickling mixture over the red onions and let sit at room temp for an hour. After an hour, cover and store in the fridge for up to 3 weeks.