Directions: 

Thinly slice red onion and place in a low bowl

In a separate bowl, stir the olive oil, red wine vinegar, balsamic vinegar, and dried oregano together to combine well.

Pour mixture over onions, making sure they are submerged.

Let sit on counter at room temperature to marinate for 12 hours before using. Keeps for 2-3 days unrefrigerated.