Peel the carrots and trim the fennel. If you're using beetroot or celeriac, peel these. Remove the outer leaves of the cabbage, if using. Shred the carrots, fennel, and your choice of radishes, beetroot, turnip or celeriac on a mandolin (use the guard), or use the julienne slicer in your food processor. Put the veg into a mixing bowl. Peel the onion and shallot, and slice as finely as you can, along with the cabbage, if using. Add these to the bowl of veg. In a separate bowl, mix half the lemon juice, a lug of extra virgin olive oil, yoghurt and mustard. Pick the herb leaves and chop, then stir into the dressing. Pour the dressing over the veg and mix well to coat everything. Season to taste with sea salt, freshly ground black pepper and the rest of the lemon juice, if you like. Really delicious served with thinly sliced leftover roast lamb, pork or rare roast beef, drizzled with extra virgin olive oil.