In a saute pan, over medium heat, melt 2 tablespoons of butter. Add the onions. Season with salt and pepper. Saute until wilted, about 2 minutes. Season both sides of the liver with salt and pepper. Season the flour with salt and pepper. Dredge
in the flour, coating completely and shaking off the excess. In a large skillet, over medium heat, melt
remaining 2 tablespoons of the butter
. When the butter is hot, add the liver. Cook for 1 minute on each side, remove from the pan and set aside.
To serve, place a serving of the gratin
in the center of each plate. Lay a piece of the liver next to the gratin. Spoon the onions over the liver. Garnish