In a small saucepan, add the vinegar, water, sugar and herbs, if using. Bring the mixture to a boil and cook until the sugar is dissolved. Allow to cool for 5 minutes.
Pour the liquid into the jars filling approximately 3/4 full. Place the lid on the jars and refrigerate for 30 minutes or overnight.
Serve as desired.
Notes
Pickled Red Onions can be made up to 5 days in advance and stored in an airtight container in the refrigerator. Great for your weekly meal prep!