Ingredients

• 2 tbsp tarragon vinegar
• 50ml/2floz white wine
• 1 tsp white peppercorns
• 1 small banana shallot
• finely diced
• 4 eggs
• yolks only
• ¼ lemon
• juice only
• 200g/7oz butter
• melted
• salt and freshly ground black pepper
• 2-3 tbsp chopped tarragon leaves
• 2 x 800g/1lb12oz chateaubriand
• fully trimmed
• 1 tbsp olive oil
• 75g/3oz butter
• 4 small stems cherry tomatoes on the vine
• 4 large chipping potatoes
• cut into 1x7.5cm/½x3in batons
• 1 large bunch watercress

Directions

• To make the béarnaise sauce
• place the vinegar
• white wine
• peppercorns and shallot into a small saucepan and bring to the boil.
• Simmer until the liquid has reduced by half.
• Remove the peppercorns then pour into a medium bowl.
• Add the egg yolks and whisk well
• then add the lemon juice.
• Place over a pan of simmering water and whisk together until thickened and light in colour.
• Gradually add in the melted butter
• whisking constantly.
• Season with salt and black pepper and add the chopped tarragon leaves.
• Turn off the heat and leave the bowl over the pan until ready to use
• For the steak
• preheat the oven to 200C/400F/Gas 6.
• Season the chateaubriand with salt and freshly ground black pepper.
• Heat a large ovenproof frying pan until hot
• add the oil and half the butter then add the beef and seal on each side until browned
• adding the rest of the butter as you go
• basting the beef with it.
• Transfer to the oven and roast for 15-20 minutes
• (depending how you like your beef).
• Remove from the oven
• turn over and allow to rest for at least 15 minutes.
• Meanwhile
• place the cherry tomatoes onto a roasting tray and place in the oven for 8-10 minutes until just bursting.
• Heat a deep fat fryer to 160C/320F. (CAUTION: Hot oil can be dangerous. Do not leave unattended.)
• Carefully place the potato batons into the fat fryer in batches and fry for 3-4 minutes
• or until tender but not coloured.
• Remove the fries then increase the heat on the fat fryer to 190C/375F and return the fries to the fryer and cook for 2-3 minutes until golden-brown and crisp.
• Remove with a slotted spoon and drain onto kitchen paper then season with salt and a little black pepper.
• To serve
• carve the rested beef into thick slices and place onto the serving plate. Pile the fries and tomatoes alongside then finish with a dollop of béarnaise and handful of watercress.