1/2 cup red wine vinegar
2 tablespoons sugar
1 tablespoon Kosher salt
1 large red onion, thinly sliced
Black peppercorns, optional
Mustard seeds, optional
In a mason jar, combine the vinegar, sugar, and salt, cover and shake to combine. Add the onions, cover, and shake. Refrigerate for at least 1 hour before using. Drain onions before using.
- You could make this up to 2 weeks in advance.