Preheat your oven to 240°C/220°C fan/gas mark 9. Fill and boil your kettle.

Take the steak and butter out of your fridge to allow them to come up to room temperature. Pour enough oil into a deep baking tray to cover the bottom and pop into the oven.

Pour the boiled water into a large saucepan on high heat with 1/2 tsp salt. Peel and chop the potatoes into 3cm chunks.

Add the potatoes to the pan of boiling water and boil for 5-6 mins or until the edges are soft.

Once the potatoes are ready, drain in a colander and sprinkle on the flour (see pantry for amount) and half the rosemary.

Shake to fluff up the potatoes, then carefully add them to the hot baking tray, turning in the oil.

Season with salt, then roast on the top shelf until golden, 30-35 mins.

Meanwhile, trim the carrots and halve lengthways. Pop onto another baking tray.

Drizzle with oil, then sprinkle with the sugar (see pantry for amount) and remaining rosemary. Season with salt and pepper, toss to coat, then spread out in a single layer.

Pop the garlic (unpeeled) into a small piece of foil with a drizzle of oil and scrunch to enclose it.

When the potatoes have roasted for about 5-10 mins, pop the garlic parcel onto the carrot tray and roast on the middle shelf of your oven until the carrots are tender, 20-25 mins.

Halfway through cooking, turn the carrots and potatoes. Remove the garlic parcel and set aside to cool.

While everything cooks, pick the tarragon leaves from their stalks and roughly chop (discard the stalks).

Pop the butter, tarragon and mustard into a small bowl. Season with salt and pepper and mash together with the back of a fork until combined.

Once the garlic is roasted and cooled, add it to the bowl of butter.

Mash again until well combined.

When about 10 mins of cooking time remain, 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. IMPORTANT: Wash your hands and equipment after handling raw meat. The steak is safe to eat when the outside is browned.

Once cooked, transfer the steaks to a plate and spread each with the flavoured butter. Cover with foil and allow to rest for a couple of mins.

When everything's ready, slice the steaks widthways into 1cm slices and transfer to your plates. Spoon over any buttery juices from the resting plate.

Serve with the roast potatoes and carrots alongside.

Enjoy!