Add all the liquids together plus the seasoning in a microwave-safe bowl, mix well, and heat in the microwave for 3 minutes. Alternatively, add the liquids together in a small saucepan, bring to a boil for 5 minutes.
Place onions in a heat-safe container such as a small mason jar, pour hot liquid, make sure onions are submerged in the liquid. Press down with a spoon if needed. Cover and set aside for at least 30 minutes to 1 hour. Enjoy. Keeps in the fridge for about 2 weeks.