Roast Beef à la Bordelaise

Remove the beef from the refrigerator and pat thoroughly dry with paper towels. Season aggressively on all sides with the fleur de sel and black pepper. Roughly chop the carrots, celery and onion; mince the shallots; dice the bone marrow; chop the parsley. Measure out all remaining ingredients.

Set the seasoned beef uncovered on a rack and rest at room temperature for 1 hour to allow the surface to dry further and the chill to leave the centre.

Begin the Bordelaise reduction while the beef rests: combine the wine, shallots, thyme sprigs and bay leaf in a medium saucepan over medium-high heat. Bring to a boil, then reduce to a vigorous simmer until the wine is reduced by two-thirds and is syrupy, about 25–30 minutes.

Add the beef stock to the reduced wine and continue simmering until the combined liquid reduces by half and lightly coats a spoon, about 15–20 minutes. Strain through a fine-mesh sieve, pressing on the solids; discard the solids and set the sauce base aside.

Preheat the oven to 230°C, or 210°C for a fan oven, or gas mark 8. Heat the oil in a large oven-safe roasting pan or cast-iron skillet over high heat until just smoking. Sear the beef on all sides until a deep mahogany crust forms, about 2–3 minutes per side.

Scatter the carrots, celery, onion, garlic, thyme and bay leaves into the roasting pan and set the seared beef on top. Transfer to the oven and immediately reduce the temperature to 180°C, or 160°C for a fan oven, or gas mark 4.

Roast until a meat thermometer inserted into the thickest part reads 52°C for rare or 57°C for medium-rare — traditional bistro doneness levels enjoyed pink as a matter of preference, not because either meets a food-safety floor: whole-muscle beef's own safe minimum is 63°C, and you're welcome to keep roasting to 60°C before resting if you'd rather it closer to that mark. Begin checking at 40 minutes and continue every 8–10 minutes until your target is reached. Carry-over heat will raise the internal temperature roughly 4–5°C during resting, so pull the roast that much below whichever number you're aiming for.

Transfer the beef to a warm plate, tent loosely with foil, and rest for 20–25 minutes — do not skip this step, as cutting early will lose all the juices. The centre will come up to about your target doneness as it rests, not lower.

Meanwhile, gently warm the strained sauce base in a small saucepan over low heat. Add the diced bone marrow and cook, stirring occasionally, until the marrow melts and emulsifies into the sauce, about 3–4 minutes.

Remove the sauce from the heat. Whisk in the cold butter cube by cube until glossy and lightly thickened. Stir in the red wine vinegar, taste, and adjust seasoning with salt and black pepper. Stir in the chopped parsley just before serving.

Remove the twine from the rested roast and slice against the grain into portions approximately 1.5cm thick. Spoon the Bordelaise sauce over the beef and serve immediately.