Chateaubriand

Instructions

1. Take the fillet out of the fridge 30 minutes before cooking and preheat the oven to 220 °C.
2. Season the piece generously with salt and pepper, then sear it in very hot oil in a pan for 2 minutes on each side until a good crust forms.
3. Brush the top with mustard, sprinkle with shallot and thyme, then roast for 12 to 15 minutes for rare meat (probe at 48 °C in the centre).
4. Let the meat rest for 10 minutes under a sheet of foil before slicing it into thick slices.
5. For the béarnaise, reduce the vinegar with the shallot and tarragon, then whisk it with the yolks over a bain-marie until it thickens.
6. Gradually whisk in the warm clarified butter, then adjust the salt and add the fresh tarragon.
7. Toss the potatoes, boiled in water, in the butter and parsley, then serve everything with the sauce.