Start by peeling the potatoes and slicing them into thin batons. Place them on a sheet of kitchen roll and pat until dry. Heat some veg oil in a saucepan over medium heat – you want the saucepan half full of oil (no more as you don’t want to risk it overflowing). Test the oil with one chip and if it bubbles, add the rest of the chips. Fry for 5 minutes then remove from the oil and allow to cool. Then heat the oil again, and fry again for a further 5 minutes. This double frying ensures maximum crispiness. Sprinkle with flakey salt when fresh out of the oil.
Halve the cherry tomatoes and add to a pan with ½ cup olive oil and the chopped garlic. Heat over medium-high and cook for 15-20 minutes with a good pinch of salt until soft and jammy.
Rub the steak with a drizzle of oil and season heavily with salt. Heat a pan on high heat and once hot, place the steak in the pan. Depending on thickness, cooking time may vary but for a 1 inch thick steak, 5 minutes a side for medium rare. Fry one side, then flip. Add butter, garlic and rosemary to the pan and spoon the juices/butter over the steak whilst the other side cooks. Remove from the pan once done and allow to rest for 10 minutes.
Make the butter. In a pan, add 1 chopped shallot and a drizzle of oil. Cook for 5 minutes over medium heat, add the red wine vinegar and cook for a further 5 minutes. In a blender, add the soft butter, cooked shallot, Dijon, tarragon, parsley and a good pinch of salt. Blend until smooth and green.
Toast the focaccia in the steak pan for best flavour, letting it soak up the juices. Then assemble. Smooth the bearnaise butter on the bottom, top with steak, jammy tomatoes, chips and rocket. Top with the other slice of focaccia.