Preheat the oven to 350°F (180°C). Line a baking tray with baking paper. Wash sweet potatoes and lay them on a baking tray. Bake for 45 minutes until they can be pierced easily with a knife. Baking will make the sweet potato soft and even sweeter but also give a nice, caramelized flavor.
Grate carrots and celeriac and onion in a food processor. This will help them cook faster.
Place a big pot on medium/high heat with 50ml of water. Add carrots, celeriac and onion with a pinch of salt, reduce the heat to medium-low, put the lid on and let the veg sweat for about 5-10 minutes until soft, stirring occasionally.
Add the turmeric and cook for a further minute.
Add the vegetable stock, pepper and the flesh of the cooked sweet potatoes.
Simmer for a few minutes until all the veg is fully cooked and flavors are nicely blended.
While the soup is cooking, blend the cashews and water in a high-speed blender until smooth.
Once the veggies are cooked, add the cashew mixture, lime juice and zest. Blend with a stick blender until smooth. Adjust seasoning as desired.
