1) Preheat the oven to 260C/Gas 10 and place a baking sheet inside to heat.
2) Add the potatoes, rosemary, sage, thyme and garlic to a medium bowl. Drizzle with the olive oil and season with salt and pepper. Remove the baking sheet from the oven, lightly coat it with olive oil and pour the potatoes onto the tray.
3) Put the potatoes in the oven and reduce the heat to 210C/Gas 7. Roast for 20 minutes, or until crispy on the outside and tender on the inside.