Ingredients (Serves 4)
Preheat the oven to 190°C, 375°F, Gas 5. Arrange the sweet potatoes, parsnips and half the carrots on a baking tray. Scatter over the spices, season with salt and freshly ground black pepper and drizzle over 2 tbsp of the olive oil. Shake the tray until all the vegetables are coated with oil, then place in the middle of the oven and roast for 45 minutes, checking and turning from time to time until the vegetables are soft and browned.
Meanwhile, heat the remaining 1 tbsp oil and the butter in a large pan with a lid. Add the red onions and cook on a gentle heat for about 5 minutes, until soft and translucent.
Add the remaining carrots, celery and leek and grind over some black pepper. Cover the pan and cook for 20 minutes, stirring occasionally to make sure the vegetables do not burn or stick to the bottom. If the mixture becomes watery, uncover the pan until all the liquid has evaporated.
Add 1.5ltr/21⁄4pt water, the roasted vegetables and plenty of salt then simmer for a further 10 minutes. Remove from the heat and leave to cool a little, then whizz in a blender in batches until smooth. Serve drizzled with a little olive oil and with warm buttered scones.