Beef Tenderloin with Sherry Jus and Confit Potatoes

This is the French dinner-party plate that never goes out of style — a properly seared tenderloin, a jus built on good Spanish sherry vinegar and reduced stock, and potatoes that have spent an hour slowly confiting in butter and garlic until they're creamy all the way through. There's nothing clever or tricky about it. The whole thing is an exercise in restraint and timing, and when you get it right, it's one of the most satisfying things you can put on a table.

How to cook

Start with the confit potatoes, because they need the most time and they're entirely hands-off once they're in the butter. Peel the potatoes (800g) and cut any larger ones so all pieces are roughly the same size — uniformity matters here because they need to cook at the same rate. Arrange them in a single layer in a heavy-bottomed saucepan or Dutch oven. Add the butter (250g) — yes, this is a lot of butter, and no, you can't use less and get the same result. The whole point of a confit is that the potatoes cook submerged in fat, slowly and gently, until they're saturated with flavour.

Drop in the halved head of garlic, thyme sprigs (4), bay leaves (2), and salt (1 teaspoon). Set the heat as low as it will go. The butter should melt, surround the potatoes, and barely murmur — if you see active bubbling, it's too hot and you're frying instead of confiting. Cook for 50-60 minutes, turning the potatoes once or twice, until a knife slides through with absolutely no resistance. They'll look pale and unassuming at this point — that's fine. The colour comes later.

While the potatoes do their thing, season the tenderloin steaks (4 × 200g) generously on all sides with fine sea salt and black pepper. Set them on a wire rack over a plate and leave them at room temperature for at least 30 minutes. This isn't optional — a cold steak thrown into a hot pan will seize up, cook unevenly, and never develop a proper crust. You want the surface dry and the core approaching room temperature.

Now build the jus. Melt the butter (2 tablespoons) in a saucepan over medium heat and add the finely sliced shallots (2 large) with a pinch of salt. Cook for 5-6 minutes, stirring now and then, until they're soft and starting to take on a light golden colour. Pour in the sherry vinegar (3 tablespoons) — use a proper Spanish sherry vinegar, Reserva grade if you can get it, because cheap vinegar will taste harsh and one-dimensional. Let it reduce until the pan is almost dry, about 1 minute. The kitchen will smell incredible at this point.

Add the dry sherry (150ml) — a Fino or Manzanilla works well — and reduce by two-thirds, about 3-4 minutes. Pour in the beef stock (500ml) and bring to a steady simmer. Let it reduce for 15-20 minutes until you have about 150ml of concentrated, glossy liquid that coats the back of a spoon. Strain it through a fine sieve into a clean pan, pressing the shallots hard with the back of a spoon to extract everything. Whisk in the Dijon mustard (1 teaspoon) — it adds body and a background warmth without tasting like mustard. Set the jus aside; you'll finish it while the steaks rest.

When you're ready to cook the steaks, heat a large heavy skillet over high heat until it's properly smoking — this is not the moment to be timid with heat. Add the neutral oil (2 tablespoons) and lay the steaks in, pressing them gently but firmly into the surface of the pan. Don't move them. Let them sear undisturbed for a full 2 minutes until a deep, dark, mahogany crust forms on the bottom. Flip them once, then immediately add the butter (30g), thyme sprigs (3), and crushed garlic (2 cloves) to the pan. As the butter foams, tilt the pan toward you and use a spoon to baste the steaks continuously, spooning the foaming, herb-scented butter over the top. This arroser technique — basting with hot butter — is what gives the steak its even colour and that aromatic, nutty finish.

A kitchen thermometer takes the guesswork out of doneness. For medium-rare, pull the steaks at 52°C internal — they'll carry over to 55-56°C during the rest. If you prefer medium, pull at 57°C. Transfer to a warm plate, spoon the basting butter over them, and rest for a full 8-10 minutes. Resting is where the magic happens: the muscle fibres relax, the juices redistribute, and the steak goes from tense and weeping to calm and uniformly rosy. Pour any resting juices into the jus.

While the steaks rest, finish the jus by reheating it gently over low heat. Whisk in the cold butter (20g) a cube at a time, letting each piece emulsify fully before adding the next. This is what gives the jus its silky, restaurant-quality body and shine. Add the resting juices from the steak plate. Taste — it should be sharp from the vinegar, deeply meaty from the stock, and just slightly sweet from the sherry. Adjust the seasoning if needed.

For the potatoes, lift them out of the confit butter with a slotted spoon and, if you want that contrast of creamy interior and golden crust, press each one gently with a fork to crack the surface slightly. Sear them cut-side down in a hot pan with a spoonful of the confit butter for 2-3 minutes until golden and crisp on the outside. Season with flaky salt.

Don't throw away the confit butter — strain it and refrigerate it. It's extraordinary for roasting vegetables, making mash, or cooking eggs for the next few days.

Bonus points

• Make your own stock: A proper brown veal or beef stock, made from roasted bones with mirepoix and reduced for hours, will elevate this jus from very good to transcendent. Even a quick pressure-cooker bone broth is a significant step up from anything in a carton.
• Tie the steaks: Wrap a loop of kitchen twine around each tenderloin before seasoning to hold its round shape during cooking. This ensures even thickness, which means even cooking and a uniform crust. Remove the twine before serving.
• Dry-brine overnight: Season the steaks with salt the night before and leave them uncovered on a wire rack in the fridge. The salt draws out surface moisture, then reabsorbs, seasoning the meat deeper and creating a drier surface for an even better sear.
• Shallot confit garnish: Peel whole shallots, toss with olive oil and thyme, wrap in foil, and roast at 160°C for 45 minutes until jammy and sweet. Serve one alongside each steak — it echoes the shallot in the jus and adds a beautiful element to the plate.
• Finish with aged sherry vinegar: Just before plating, add a few drops of a 25- or 50-year aged sherry vinegar directly onto the sliced steak. The concentrated sweetness and acidity are astonishing against the beef.
• Bone marrow butter: Roast marrow bones at 200°C for 15-18 minutes, scoop out the marrow, and fold it into softened butter with a pinch of flaky salt and chopped parsley. Melt a coin of it on top of each resting steak for obscene richness.
• Smoked potatoes: Before confiting, cold-smoke the peeled potatoes for 20 minutes using a stovetop smoker or smoking gun. The subtle smokiness running through the buttery, garlicky potato is extraordinary.

Serving

Slice each tenderloin against the grain into three or four thick medallions and fan them slightly on a warmed plate, showing off the rosy interior. Spoon the sherry jus generously around — not over — the beef, so the crust stays dry and the jus pools on the plate. Arrange the confit potatoes alongside, golden side up, and finish with a pinch of flaky sea salt on both the meat and the potatoes.

For a more casual approach, serve the tenderloin whole on a board with the jus in a warm jug and the confit potatoes piled in a bowl. Let people slice and serve themselves.

Keep the sides simple — this plate doesn't need competition. A handful of watercress dressed with nothing but lemon juice and olive oil, or haricots verts blanched and tossed in a little of the confit butter, is all you need for colour and freshness.

For wine, this is textbook Bordeaux territory — a mature Saint-Julien or Pauillac with firm tannin and cedar notes is the classic pairing that works every time. If you lean Burgundy, a Gevrey-Chambertin or Nuits- Saint-Georges with a few years of age brings earthiness that complements the sherry jus beautifully. For something less expected, a dry Palo Cortado sherry mirrors the vinegar in the jus and creates a seamless thread from glass to plate.