Start by thinly chop the onion and add it to a pan with some olive oil Cook on low heat until the onion is soft but not brown. Add the cabbage and mix well so that it takes the flavour from the onion. Add a glass of water, cover and cook for 5 minutes or so until the cabbage starts to soften up
Add the milk to the soup, cover and let it cook for 15 minutes or so on low heat.
Mix with a hand held blender until it's a smooth consistency. Remove a ladle worth of soup into a bowl and add the lemon juice, mix and watch the magic happens.
Serve the purple soup and use the now pink soup to make a nice decoration on top. I would probably suggest to have a slightly more liquid consistency then what I have done here.
