1 small red onion, sliced 1/8″ thick (I like using my mandoline)
1/2 cup red wine vinegar
1 tablespoon olive oil
1 teaspoon kosher salt
Place the sliced onions in a wide mouth pint mason jar.
Pour the red wine vinegar mixture over the onions, and cover with a lid.
Allow to marinate at room temperature on the counter for at least 8 hours.
Will keep refrigerated for at least 2 weeks.