Dried Pea Soup

Take one quart of split peas, or Lima beans, which are better; put them in three quarts of very soft water with three onions chopped up, pepper and salt; boil them two hours; mash them well and pass them through a sieve; return the liquid into the pot, thicken it with a large piece of butter and flour, put in some slices of nice salt pork, and a large tea-spoonful of celery seed pounded; boil it till the pork is done, and serve it up; have some toasted bread cut into dice and fried in butter, which must be put in the tureen before you pour in the soup.