Preheat your oven to 220°C/200°C fan/gas mark 7.

Remove the steaks and butter from the fridge to bring them up to room temperature. 

Halve the salad potatoes widthways and put them on a baking tray. Drizzle with oil, season with salt and pepper, then toss to coat. Spread out in a single layer, cut-side down.

When the oven is hot, roast the potatoes on the top shelf, 20 mins. 

When the potatoes have cooked for 20 mins, remove them from the oven. Use the bottom of a bowl or pan to lightly crush each potato half.

Drizzle the smashed potatoes with more oil and return to the top shelf until crispy and golden, 10-15 mins.

While the smashed potatoes roast, put the butter into a small bowl and mash with a fork until soft.

Finely chop the parsley (stalks and all, see ingredients for amount). 

Stir the sun-dried tomato paste and half the chopped parsley through the butter. Set aside.

About 8 mins before the potatoes are cooked, heat a drizzle of oil in a large frying pan on high heat. Season the steaks with salt and pepper.

Once hot, lay the steaks into the pan and fry until browned, 1 min on each side. Lower the heat slightly and cook for another 1-2 mins on each side if you want them medium-rare. TIP: Cook for 1-2 mins more if you like it more well done.

Transfer the steaks to a plate, top with the tomato butter and cover loosely with foil. Allow to rest.

While the steaks rest, return the (now empty) frying pan to high heat with a drizzle of oil.

Once hot, add the spinach in handfuls until wilted and piping hot, 2-3 mins.

Once wilted, stir through the wholegrain mustard. Season with salt and pepper.

When the smashed potatoes are ready, remove them from the oven and toss through the mustard spinach.

Slice the steaks widthways into thick slices and serve with the mustard smashed potatoes alongside. 

Spoon the sun-dried tomato butter from the resting plate over the steaks and finish with a sprinkling of remaining parsley.

Enjoy!