Cut two pounds of calf's liver into square pieces, and put them in a sautoire with one ounce of clarified butter. Season with a tablespoonful of salt and a teaspoonful of pepper, and add two medium-sized, sliced onions. When well stewed for six minutes, pour in a teaspoonful of vinegar, and two tablespoonfuls of Espagnole sauce (No. 151), and let it just come to a boil. Serve with a little chopped parsley.