White Bean Soup

Description
Like Simplest Split Pea Soup, this makes the transition from simple to complex quite readily.
 * Contributed by Catsrecipes Y-Group
 * Source: How to Cook Everything
 * Time: at least 1½ hours
 * Makes 4 servings

Ingredients

 * 1½ cups navy, pea, or other dried white beans, washed and picked over
 * about 6 cups chicken, beef, or vegetable stock, or water, plus more if necessary
 * 1 medium onion, quartered
 * 2 tbsp butter or extra-virgin olive oil (optional)
 * salt and freshly ground black pepper to taste
 * minced fresh parsley leaves for garnish

Directions

 * 1) Place the beans, stock or water, and onion in a large, deep saucepan or casserole; turn the heat to medium-high.
 * 2) When it boils, turn the heat down to medium-low and cover partially.
 * 3) Cook, stirring occasionally, until the beans are very soft, at least 1 hour.
 * 4) Put the mixture through a food mill or strainer, or puree it in a blender (you may prepare the soup in advance up to this point. Cover, refrigerate for up to 2 days, and reheat before proceeding).
 * 5) Reheat, adding more stock or water if necessary to achieve the consistency you like.
 * 6) Stir in the butter or oil, season with salt and pepper, garnish, and serve.