A great topping for nachos, hot dogs, tacos, and burgers!
Thinly slice the red onions and place into 3 pint size mason jars. Add peppercorns, garlic, or herbs if desired.
In a saucepan, mix together the vinegar, water, sugar, and salt. Bring to a boil, reduce heat to low and simmer for 1 minute, stirring constantly.
Carefully pour the vinegar mixture into the mason jars, covering the onions completely.
Place in the fridge for at least 24 hours before eating. Can be stored in the fridge for up to 6 months.