Pickled Onions for Yucatan Tacos – – cider vinegar, oregano, salt, black pepper, cumin (ground ), garlic powder ((use fresh garlic, if preferred)), red onion (peeled and sliced), salt, Make the pickling liquid by combining the vinegar, oregano, salt, black pepper, cumin and garlic in a glass bowl.; Peel and thinly slice the red onion and blanch in a pot of boiling salted water for 1 minute. Drain and place the onions in pickling liquid.; Let stand at room temperature for 2 hours.  The onions will turn pink and soft. Refrigerate until served.; –