Chop the carrots and the sweet potato into chunks and lay them out on a baking tray. Drizzle with oil and toss to coat everything.
Chop the onions into wedges, leaving most of the skin on. Place these on another baking tray with the cloves of garlic, in their skins. Drizzle with oil and toss to coat everything.
Place everything in the oven for 30-40 minutes until completely soft. When cooked, take them out to cool.
Boil 1.5 litres of water and dissolve the vegetable stock into it.
Peel any remaining onion skins off and peel off the garlic skins.
Add the onions and garlic and some of the cooked vegetables to a high-speed blender with some of the stock and blend until completely smooth. You will most likely need to do this in batches as there is a lot of volume here to fit all at once. Keep blending the vegetables with the stock until it is all completely smooth.
Add all the soup back into your blender (if possible – otherwise, do it in batches) and add the grated ginger, milk and 4 tbsp of miso. Blend and taste, add another 1 tbsp of miso if you like.
Serve warm with sliced spring onions, a squeeze of lime, cracked black pepper and a drizzle of the cream of your choice.