Mushrooms are washed well and if they are small leaving targets if medium-sized cut into triangular pieces 4 or 6, if it is larger. High heat to heat the oil (olive oil) and the butter. As become hot fat, add the mushrooms. Stir until well browned and remove from heat. If you enjoyed onion, it is added and cook on medium heat for about 2 minutes. Mushrooms are seasoned with salt and pepper just before serving. * The recipe is adapted from the book * Mastering the Art of French Cooking * Julia Child, Luizet Berthollet and Simon Beck. * Mushrooms are used in the preparation of Beef Burgundy * * * * Chicken with wine, and others.