Heat the oven to 220C/200C fan/gas 8. Add the oil to a large flameproof baking tray and put in the oven to heat up.

Bring a large pan of salted water to the boil, tip in the potatoes and their peel (for extra flavour), and simmer for 8-10 mins. Drain the potatoes and discard the peel. Leave to steam-dry for 15 mins, then return the potatoes to the pan, put the lid on and gently shake to lightly rough up the edges.

Remove the tray from the oven and put directly on the hob over a medium heat. Add the butter to the hot oil and, using tongs, add the potatoes to the tray, one by one, turning them in the fat, leaving a little space between each. Reduce the oven to 200C/180C fan/gas 6. Nestle the herbs around the potatoes, along with the garlic. Sprinkle over 1 tbsp sea salt and return to the oven for 1 hr, turning every once in a while, until golden and crisp.