Ingredients:
4 c. peeled and very thinly sliced red onions (a mandolin works great!)
1 c. Tubby Olive Champagne White Vinegar
½ c. water
¼ c. Tubby Olive 18 Year Traditional or Tubby Olive White Premium Balsamic
½ c. sugar
1 Tbsp. salt
2 tsp. mustard seeds
2 tsp. dried oregano
1 tsp. coriander seeds
½ tsp. peppercorns

Directions:
Place the red onions in a 1 liter (4 cup capacity) sterilized glass jar. In a small saucepan, heat the remaining ingredients until the sugar has dissolved then pour over the red onions, ensuring the onions are completely covered. Place the lid on the jar and allow to cool before refrigerating for at least 24 hours before serving. These pickles will last for up to 1 month in the refrigerator. Use on tacos, burgers, sandwiches and more!
Photo and modified recipe from Simply Delicious.