Preheat oven to 150ºC/gas 2-3. Scrub the parsnip, carrots and beets. Using a mandolin or the thick slicer on a grater, slice each of the veg at an angle into long pieces – they really shrink in the oven. Place veg slices in a single layer on baking trays – keep the veg separate. Place the carrots and beetroots in the oven for about 2 hours; after 30 minutes add the parsnips. Remove when dry, crisp and cooked. Crush the salt, fennel seeds and chilli in a mortar (or a coffee grinder), and sprinkle over your crisps. Serve hot or cold.