Step 1

Thinly slice the red onion and place in a low bowl.

Step 2

In a separate bowl, stir the olive oil, red wine vinegar, balsamic vinegar, and dried oregano together to combine well. Pour the mixture over the onions, making sure they are submerged.

Step 3

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