Season the steak on both sides with salt and pepper. Heat a frying pan until hot. Add a splash of sunflower oil, then sear the steak on either side so it is nicely caramelised. Lower the heat and cook for 2 to 3 minutes on each sides. remove from the pan and allow the steak to rest. Reserve the resting juices for the mushroom sauce.
Bring the potatoes to the boil from cold water with a generous pinch of salt. When boiling, reduce the heat to a simmer and cook for 20 minutes or until tender. Drain, crush with a fork and mix in the truffle oil.
Chop the tarragon and leave to one side. Peel and finely dice the shallot. Pod the broad beans. Tear the oyster mushrooms into strips.
Sweat the mushrooms in half of the butter over a medium heat for a few minutes before adding the shallot. Cook for a couple of minutes and then add the podded broad beans. Add the resting juices from the beef and the remaining butter. Allow juices and butter to emulsify together and coat the vegetables. Add the tarragon just before serving.
Place the crushed potatoes in a ring in the centre of the plate. Slice steak and fan around. Top the steak with the mushrooms and drizzle the sauce around the plate.
«Use any mushrooms that are readily available in the supermarket. Add peas instead of broad beans.»