Split Pea Soup

1 cup dried split peas

2½ quarts cold water

1 pint milk

½ onion

3 tablespoons butter

2 tablespoons flour

1½ teaspoons salt

⅛ teaspoon pepper

2–inch cube fat salt pork

Pick over peas and soak several hours, drain, add cold water, pork, and onion. Simmer three or four hours, or until soft; rub through a sieve. Add butter and flour cooked together, salt, and pepper. Dilute with milk, adding more if necessary. The water in which a ham has been cooked may be used; in such case omit salt.