PACK onions into two 500 ml jars, or one 1 L jar.
BRING vinegar, water, sugar, salt and chilies to a boil in a medium saucepan. Remove from heat. Pour hot liquid over onions into jars, leaving ¼ inch space from the top. Let cool to room temperature.
CLOSE jars and store refrigerated. Onions will keep for up to 10 days.
