Half-fill a large pan with water. Add a large pinch of salt. Cover and put on a high heat to come to the boil. Preheat your oven to 200°C/Fan 180°C/Gas 6.

Scrub and peel the potatoes. Chop them into roughly equal-sized chunks, around 3-4cm across. Pop them in a large colander and rinse under cold water to get rid of some of the starch. When the water in the pan is boiling, add the potatoes. Bring back to a gentle simmer, and then simmer for 5 mins.

Drain the potatoes, then tip them back into the pan. Gently shake them to rough up the edges (this will help the potatoes crisp up in the oven). Lay a couple of clean tea towels out on your kitchen surface and tip the potatoes onto them. Spread the potatoes out and let them steam-dry for up to 10 mins (no longer than that or the potatoes will develop a ‘skin’ and become leathery).

Meanwhile, add 4 tbsp oil to a large roasting tin (or 2 medium tins). Put them in the oven to heat the oil for 10 mins.

Take the roasting tin out of the oven. Add the spuds to the tin and season with a pinch of salt. Turn them a few times to coat in the hot oil. Make sure the potatoes aren’t too crowded in the tin – it’s better to use two tins and give the spuds room to roast, rather than cramming them in so they end up steaming. Roast for 45 mins, turning them after 20 mins, till they’re golden brown.

While the potatoes roast, pick the thyme leaves off the woody sprigs (push them through a sieve and the leaves will collect in the bowl of the sieve). After 45 mins, remove the tin from the oven and scatter over the thyme. Turn the potatoes a few times and return to the oven for 5-10 mins till golden brown and crisp. Transfer to a dish and serve.