Step 1 Heat the oven to 200c fan.

Step 2 Bring an oven-proof cast iron pan up to searing temperature - the hottest you can get it. Score the fat and rub all over with vegetable oil before seasoning generously with salt and pepper.

Step 3 When the pan is scorching hot, use tongs to place the steak in the pan and allow it to sizzle for 30 seconds until it browns. Repeat on all sides, until you’ve coloured the beef all over.

Step 4 Place in the oven for approximately 45 minutes for medium rare (for 2kg of beef). Crucially, use a meat thermometer and remove from the oven when it hits a core temperature 54-57c. Set aside to rest for 15 minutes on a chopping board or plate, covering the joint with foil.

Step 5 To make the bearnaise sauce, place the vinegar, lemon juice, shallots and half the tarragon in a pan over a high heat and bring the boil. Allow it to reduce by half, before straining the mixture and setting aside.

Step 6 Add the egg yolks to a bowl over a bain-marie and whisk until the mixture is fluffy and coats the back of a spoon.

Step 7 Remove from the heat and very slowly, trickle in the melted butter, while whisking continuously. If the mixture looks like it’s about to split, add a splash of cold water and carry on.

Step 8 Add the remaining chopped tarragon and season to taste with salt, pepper and lemon juice.