– Toast Mexican oregano in a small skillet over medium-high heat for about 30 seconds. Set aside to cool.
– Peel onions and thinly slice them. Place 4-5 cups of water in a saucepan and bring to a boil.
– Place the drained onions in a glass bowl and add the vinegar, water, oregano, bay leaf and the rest of the spices. Season with salt and mix well. Refrigerate for a couple of hours, and they are ready to eat. They keep well refrigerated for about a week. And they taste best when prepared at least one day in advance.