Remove the livers to a baking sheet, separating them.
05Heat 2 tablespoons of the oil in a large nonstick skillet over high heat. Add half of the livers one at a time. Cook, turning the livers as they brown. One batch of livers takes about 4 to 5 minutes to cook. Drain the livers. Wipe out the skillet, and add the remaining 2 tablespoons oil. Cook the remaining livers the same way, then drain.06Using the same skillet, heat the remaining 2 tablespoons of butter over high heat. Add the livers, cooked onions, sage, salt and pepper. Cook, shaking the skillet and tossing the livers so they will heat throughout. Add the vinegar, stir and blend well for about 2 minutes. Sprinkle with parsley, and serve immediately.