Preheat the oven to 220'C.
Use a sharp knife to make incisions in the beef fillets. Insert the sage into the incisions and season with salt.
Heat a frying pan and add a little olive oil. Colour both sides of the fillets and then remove from the pan. Allow to rest for at least 5 minutes before placing in the oven and cooking for 8 minutes.
Wash all of the mushrooms and trim if necessary. Heat a pan with olive oil and first add the cepes. Season with salt then add the girolles, oyster mushrooms, white mushrooms and finally the trompette de la mort mushrooms. Season with salt each time you add a new variety of mushroom. Add the garlic and the chopped parsley and season once more.
Serve the beef on a bed of mushrooms.
«Vary the mushrooms according to taste, season and availability.»