Sauté the onion in 1 oz. butter and 2 tbs. oil in a covered skillet over a low heat. When the onions are cooked and the liquid is reduced, add some finely minced parsley. Set aside and keep hot.
Season the liver slices with salt and pepper. Sauté the slices of liver on each side very quickly in 1 oz. butter and 2 tbs. oil over a high flame, turning with a wooden spatula to avoid pricking it with a fork. Sprinkle with the wine and remove from heat.
Arrange the liver on a pre-heated serving platter. Serve topped with onion soffritto and serve.
