These onions go really well with
, at the taco bar or any other time you want a milder tasting onion. Start them earlier in the week or at the very least, the day before you want to serve them.
Thinly slice onion while heating water. In a small bowl add sugar and salt. Add hot water to dissolve and mix in cider vinegar. Let cool before placing onions in the liquid.
Put onions in a glass container with tight lid and refrigerate for at least 24 hours and up to 3 days.
*The longer the onions marinate, the more mellow they become.