Potato Soup (Vichyssoise)

REAL vichyssoise is a chilled soup, but I think I like it better hot. The original soup has a lot of butter and heavy cream, so I've made some not-insignificant changes in veganizing it, but it still tastes good!

Ingredients:
-around13 pounds of potatoes (very small ones, if possible)
-enough water or vegetable stock (you can use Rapunzel vegan bullion cubes if you're on a tight budget) to boil the potatoes in (this can vary a lot)
-vegan butter (around 1/2 cup)
-around 10 leeks
-around 5 cups soy creamer, soy milk thickened with flour, heavy cream, or other creamy-textured liquid
-3 large sweet onions
-salt and pepper to taste
-vinegar (I think balsamic is nicest)

Wash the potatoes and chop them in to 1-inch cubes. Carefully clean the leeks (they always have lots of mud inside). Chop them, and throw away the toughest outer green leaves, but try to use the tender inner green leaves (no point in ONLY using the white part). Melt the butter in a skillet and sautee the leeks until they are soft, but not browning. Meanwhile, chop the onions. Then put the sauteed leeks in your soup pot and add the water/stock, potatoes and onion. Boil until the potatoes are cooked. Then add the soy creamer, soy milk, or heavy cream. Add salt and pepper to taste. Then blend the soup in a blender until it is completely smooth (it'll still have chunks of potato skin, though). Last, add vinegar to taste. Garnish with any green herb.