Serves 4 or more
1. Trim the leeks of the roots and their green leaves,then slice them and rinse them well. Thinly slice the onion. Quarter the potatoes lengthwise and thinly slice them as well. Grate the parsley roots if you have them.
2. Melt the butter in a wide soup pot and add the leeks, onion, potatoes, parsley roots, and bay leaves. Cook over medium heat for about 7 minutes, stirring occasionally. Raise the heat, add the wine, and let it reduce until syrupy. Add 1 1/2 teaspoons salt, and 6 cups of the water or stock. Bring to a boil then lower the heat and simmer, partially covered, until the potatoes have broken apart, about 30 minutes. Add the parsley during the last 15 minutes, and more water or broth if it seems to think.
3. Remove the bay leaves and blend about half the soup until smooth. Return it to the pot. Taste for salt and season with pepper.
Serve with any additions you wish.