Peel the potatoes, sweet potato and carrot and cut into pieces. Then wash and quarter the Jerusalem artichoke and radishes. Do not peel!
Put the vegetables and milk in a saucepan and simmer for about 20 minutes with a pinch of sea salt on medium heat with the lid slightly open. Stirring occasionally.
Meanwhile, wash the spring onions and cut into rings.
Take the pot off the stove and use a hand blender to make an even, slightly chunky puree. Season to taste with nutmeg and salt and pepper.