Pickled onionsSauce, Side Dish Ingredients: 1 big red onion ½ cup champagne vinegar or white vinegar 2 Tbsp. EVOO Salt to taste Peel the onion and slice it thinly. Sauté the onion with the olive oil in a pan and, when it starts to become translucent, add the vinegar. Keep cooking on medium/high heat until most of the vinegar has evaporated.