Have your ingredients measured and ready. You'll also need a clean sterilized glass jar with a rubber seal gasket (dishwasher or boil in hot water).
Cut off the onion ends, peel, and slice your onion. We like them not too thin nor too thick.
3 medium Red Onions
Pack the onion slices into the clean jar.
Add the salt and sugar, and pour in the vinegar and water so that the onions are submerged.
1 Tablespoon Salt, 1½ Tablespoon Sugar, 1 Cup Vinegar, 1 Cup Water
Close the jar tight and shake it so that the sugar and salt get dissolved.
Keep the jar out for 2–3 days at room temperature and shake the jar briefly daily at least once.
After the 2–3 days out, store the jar in your fridge at all times. The flavor will develop further in time, but you can use and enjoy your onions in your food already.
Notes
1 pint jars = 16 ounce jars = 500 milliliter (½ liter) jars. We use leakproof glass clamp jars with rubber gaskets. Get quality glass jars and rubbers if possible, the rubbers can be replaced. Ikea has cheaper ones too.The water and vinegar ratio is always 1:1.If you have a little space for more liquid to top up the jar, finish off with a small quantity of water.