Basic Brown Onion Soup

Instructions:
Skin and cut in slices six large onions; fry them in butter till they are a nice brown and very tender, then lay them on a hair-sieve to draw out the butter. When drained, put them in a pot with five quarts of boiling water, boil them one hour, and stir frequently; then add pepper and salt to your liking, with some crumbs of bread rubbed through a colander; stir it well to keep it from being in lumps, and boil it two hours more. Ten minutes before you serve the soup, beat the yolks of two eggs with two spoonfuls of vinegar, and a little of the soup, and pour it into the remainder of the soup by degrees, stirring it all the time one way. If you choose, you can add a few cloves. This is a fine soup and will keep three or four days.