3 min prep time
2/3 cup red wine wine vinegar
2/3 cup water
1 tbsp. Kosher salt
1/2 tsp. sugar
1 medium red onion, thickly sliced into 1/4- to 1/2-inch rings (about 1 cup)
1. Mix together the vinegar, water, salt, and sugar in a medium bowl. Microwave the mixture until steaming, about 1 minute.
2. Add the onions, mix, and set aside. When cooled, cover and refrigerate until ready to use.
The onions can be prepared up to 2 weeks before using.