Steak frites sandwich with peppercorn sauce mayo

Peel and slice the potatoes into thin chips – around 1cm thickness. Place into a bowl and cover with cold water. Soak the chips for at least a couple of hours, to remove starch and ensure a crispy result

To make the peppercorn sauce, transfer one third of the peppercorns to a pestle and mortar and crush them roughly

Melt the butter in a frying pan and add the shallots and all the peppercorns. Cook until the shallots have softened but not coloured

Add the red wine and let it bubble down until reduced by half

Add the Worcestershire sauce and stock and reduce by half again

Remove the sauce from the heat and stir in the cream. Check the seasoning and add salt if necessary, then cover and set aside

Next, cook the steak. Heat a heavy based frying pan or griddle over a high heat

Rub the steak lightly with oil and season very well with flaky sea salt

Once the pan is very hot, add the steak - it should sizzle and smoke dramatically (you might want to open a window at this point!)

Cook for a minute or two each side - the exact cooking time will depend on the thickness and shape of your steak. For medium rare meat, a probe thermometer should read 52ºC when inserted into the thickest part of the steak

Once cooked to your liking, remove the steak from the pan and set aside to rest while you cook the fries

Heat oil for deep-frying to a temperature of 140ºC. Cook the fries for around 6 minutes, or until they are a light golden colour and a little crispy

Drain on kitchen paper

Increase the temperature of the oil to 180ºC, then fry the fries a second time, until golden brown and crisp - this will only take a couple of minutes. Drain on kitchen paper once more

Make the peppercorn sauce mayo by combining 2 tablespoons of the peppercorn sauce with the mayonnaise and mixing well

Tip any resting juices from the steak into the remaining peppercorn sauce and gently reheat it, then tip into a small serving dish

To assemble the sandwiches, slice the baguette lengths and spread one side with mustard and the other with the peppercorn sauce mayo

Top with sliced steak and a generous handful of fries, then close the sandwiches and serve the remaining sauce on the side, for dipping