Add water, white vinegar, sugar, and salt to a small saucepan. Heat the mixture until the sugar and salt have completely dissolved.
Peel and thinly slice the red onions. Transfer to a large jar, and pour the liquid over them, ensuring they are fully covered. Leave on the counter until cool down, then transfer to the fridge.
Store the jar in the refrigerator for up to 2 weeks. The onions will be ready to enjoy after 3 hour, but for best results, let them sit overnight.
Video
Notes
Flavor adds-on: add peppercorn or finely sliced jalapenos to the jar, for an extra kick.
Nutritional Information - Per Serving
Calories 5kcal | Carbohydrates 1g | Sodium 30mg | Vitamin C 1mg | Calcium 3mg | Iron 5mg