Zesty layered potatoes

Preheat the oven to 200°C/gas mark 6. Slice the potatoes very thinly with a sharp knife or mandoline and rinse with water. Transfer to a large bowl. Melt the butter in a saucepan. Mix in the chopped herbs, then zest the lemons into the butter mixture. Season and mix thoroughly. Add the butter mixture to the potatoes and coat well, then transfer the potato slices to a baking dish, arranging them in vertical layers. Season and bake for 45 mins. Garnish with the extra herbs and serve.