1. Chop the potato and onion into 1-2cm chunks and place in a large saucepan.

2. Make up 600ml of vegetable stock and add to the pan with the potato and onion, also add in the lemon juice. Cook these root vegetables for about 20 minutes on a medium heat until beginning to soften.

3. Once the potato is starting to soften but not quite fully soft, add in the kale and cook for a further 6-8 minutes.

4. Once kale is wilted and the potato soft add in the spinach and chilli flakes and cook for a couple more minutes until the spinach has fully wilted. Season with salt and pepper.

5. Cool the soup slightly then pour into a blender and blitz for a minute or two until fairly smooth. Serve hot, or allow to go cold and freeze in portions.