- ½ cup apple cider vinegar, sherry vinegar, or red wine vinegar
- 1 tablespoon sugar or honey
- 1½ teaspoons kosher salt
- ½ cup water
- 1 red onion, thinly sliced
- Whisk vinegar, salt, sugar, and water in a small bowl until sugar and salt dissolve. Place onion in a jar; pour vinegar mixture over. Let sit at room temperature for at least one hour.