I've made this soup a couple of times at my work, and it's been a pretty big hit. The Lovemuffin eats a lot of it when I make it at home, too, so that usually a good indicator of a good recipe.
Here's what you do:
Peel 3 large russet potatoes, chop into pieces, put them into a pan and fill with just enough vegetable broth and water to cover the potato pieces. Add some black pepper and oregano and dill, if desired, to the pot. In the meantime, clean and chop 3 leeks, just the white and light green part, into thin slices. Peel and chop one onion into pretty small pieces. Saute the leeks and onion in butter or olive oil until they are translucent and tender. When the potatoes are soft and the leeks are tender, blend the potatoes with the broth in a blender until smooth or mostly smooth. You might not need all of the liquid.
Put the blended potato stuff back in the pot, add the sauteed leeks and onions and about a cup of half and half. Let it simmer for a few minutes, it will thicken a little, you can add milk or water if it is too thick. Add salt and pepper to taste, and consume.