- 1kg/2lb 4oz chipping potatoes
- groundnut or sunflower oil, for deep frying
- 50ml/2fl oz white wine vinegar
- ½ tsp black peppercorns
- 1 small shallot, finely chopped
- 1 large sprig of tarragon, bruised
- 3 free-range egg yolks
- 200g/7oz unsalted butter, cubed and softened
- squeeze of lemon juice
- 3 tbsp tarragon leaves, finely chopped
- freshly ground white pepper
- 2 x 200g/7oz sirloin or rib eye steaks, about 2cm/¾in thick, at room temperature
- flaky sea salt and freshly ground black pepper
- For the chips, cut the potatoes into thick batons and rinse them in cold water to remove as much starch as possible, put them in a large saucepan. Cover the chips with cold water and slowly bring to the boil. Simmer gently for 20–25 minutes, until the potatoes are knife tender and you can see lines and cracks start to develop. Using a slotted spoon, carefully remove the chips from the saucepan, don’t tip them into a colander as they will fall apart. Drain on kitchen paper and gently pat dry.
- Meanwhile, for the sauce put the vinegar, peppercorns, shallot and tarragon into a small saucepan, add 50ml/2fl oz water and bring to the boil. Simmer until the liquid has reduced to about 2 tablespoons. Strain and reserve the liquid.
- Place a heatproof bowl over a saucepan of simmering water. Make sure the bottom of the bowl doesn't touch the water. Put the egg yolks, a cube of butter and a pinch of salt into the bowl. Whisk them together, then add half the reserved liquid. Whisk until the mixture emulsifies and starts to thicken, then gradually add all the butter, a cube at a time. Make sure the mixture is emulsifying and not separating before adding more butter. If it starts to get too thick, add a teaspoon of warm water.
- When you have added all the butter, remove the bowl from the pan. Add a squeeze of lemon juice and stir in the tarragon leaves. Taste for seasoning and acidity and add salt, pepper and more of the reserved liquid if necessary. The sauce will keep warm for up to 30 minutes. Leave it in a heatproof bowl but off the heat.
- To fry the chips, heat a deep fat fryer to 130C. Fry the chips, in batches, for 5 minutes, remove and set aside (CAUTION: hot oil can be dangerous. Do not over-fill the pan or leave unattended).
- Meanwhile, pat the steak dry with kitchen paper. Head a griddle pan for several minutes over a high heat until it is too hot to hold your hand over – don’t ever touch the pan. Season the steak with plenty of salt. Add the steaks to the griddle, making sure you don’t overcrowd the pan.
- For a very blue or rare steak cook for 1 minute on each side. For rare cook for 1½ minutes, for medium rare cook for 2 minutes and then 1½ on the other side. For medium cook for 2 minutes on each side. Remove the steaks and rest them for 5 –10 minutes, so the meat can relax and hold on to more of its juices. Season with black pepper.
- Increase the deep-fat fryer temperature to 180C, return the chips to the pan, in batches, and fry for 1–2 minutes or until they are crisp and deep golden-brown. Drain on kitchen paper, then sprinkle the chips with salt.
- To serve, carve the meat into slices and pour the sauce over the top and serve the chips alongside.