Heat the olive oil in a large pan and add the onions, cabbage, leeks and potatoes, stirring to combine. Cover with a lid and sweat over a medium heat for about 5 minutes until softened but not coloured.
Add the tomatoes to the pan, season to taste and allow to cook for a couple of minutes.
Pour in the wine and allow to reduce by half, then add the stock or water and bring to the boil.
Reduce that heat and leave to simmer for 15 minutes until all of the vegetables are completely tender and the liquid has slightly reduced and thickened. Season to taste.
To Serve: Ladle the soup into warmed serving bowls and garnish with the parsley.