We are having it for supper tonight with grilled cheese sandwiches. Here is the recipe I use which is Julia Child's recipe. A version of this recipe appears in almost every one of her cookbooks - a true miracle food and French basic. Since I want to give proper credit, I will source The Way To Cook.
Basic Leek and Potato Soup
2 TBLS butter
3 cups sliced leeks, white and pale green
1 1/2 cups sliced onions (about 2 medium)
2 TBLS flour
6 cups water
4 cups peeled, diced potatoes
1 1/2 tsp. Salt
1/2 tsp freshly ground white pepper
Melt butter in the saucepan over moderate heat. Stir in the leek and onion pieces to coat with butter, cover the pan, and reduce the heat. Cook slowly, stirring occasionally, for 10 to 15 minutes, until the vegetables are very soft, but not colored. Uncover, sprinkle on the flour, stir to distribute and cook for 2 minutes. Remove from heat and let cool. Stirring continually, gradually pour in 1 1/2 cups of water and bring to simmer. When the liquid is smooth and starts to thicken, stir in the rest of the water. Add the potatoes and season. Quickly heat the soup to a gentle boil, cover, and lower the heat. Simmer about 20 minutes until potatoes are tender. Correct seasoning. To serve, mash, blend, or puree the soup to the desired consistency and adjust the seasoning. Garnish.
Don't panic! If you don't grow leeks or you can't buy them, just use onions. If you don't eat wheat flour, just use some other thickener. If you don't have white pepper, use black, but know that black specks floating in white soup isn't beautiful (My grandfather coated his in black pepper, but Julia Child has a hang-up about it). I prefer this soup (when no one is looking) chunky, so I take an old fashioned potato masher and just smash around a little, but you can dress this soup so it becomes fancy fare.
Make no excuses, there is nothing other than healing goodness in this soup. And, if you puree you can claim that you have produced vichyssoise. Heal yourself.