Ingredients

• 1 small red onion
• ~¹⁄₂ cup red wine vinegar

Method

• Cut the onion in half lengthwise and slice thinly across (~¹⁄₈″)
• Put slices in a 16oz mason jar
• Fill the jar with red wine vinegar
• Cover and shake
• Let sit a few hours (at least) in the fridge

Notes

This lasts a couple of weeks in the fridge.