1. Thoroughly wash the leeks and remove any dark green leaf.
2. Cut in thin slices.
3. Melt butter in a pan, add leeks, cover with a lid & cook on low heat until tender without colouring.
4. Add the water and Major Light Vegetable Stock Base Paste and stir well until dissolved. Simmer for 10 minutes.
5. Cut potatoes into small squares and add to leeks and stock.
6. Bring to the boil and simmer until the potatoes are tender but not broken up.
7. Season with pepper.
8. Mix the milk and cornflour together and stir into soup and simmer for 2 minutes.
9. Blitz slightly.