First grow leeks!
Then dig up leeks.
For four mugs of soup I use 3 or 4 leeks, 2 medium potatoes and vegetable stock.
Slice the leeks finely. Peel the potatoes and cut into small cubes (half-inch). Place in saucepan, add enough stock to cover, bring to the boil and then simmer for about 30 mins. I then process the soup to give a creamy consistently adding more stock (or milk) if necessary.
Top with black pepper and serve.