1. Warm the oil and butter together in a saucepan and add the chopped onion.
2. Cover with a lid and cook over a medium heat for a few mins before adding the curry powder.
3. Add the potato and continue to cook for a further 5-10 minutes
4. Pour the milk and water over the potatoes, then sprinkle in the vegetable stock cube.
5. Bring to a simmer and cook for 15-20 mins until the potatoes are completely tender.
6. Season with a pinch of salt and blitz in a blender until smooth.
7. For a slightly sweet touch, add the mango chutney, a teaspoon at a time to suit your taste, liquidizing until smooth.
8. Divide the soup into bowls, finishing with the cilantro leaves if you have them.