Pennsylvania Dutch Potato Soup
["1 small onion", "1 stem celery", "3 medium potatoes", "1 qt. water", "1 1/2 tsp. salt", "pepper to taste", "2 c. milk", "1 Tbsp. flour", "2 Tbsp. butter or margarine", "2 Tbsp. parsley", "1 hard-boiled egg (optional)"]
["Chop onion and celery.", "Peel and dice potatoes into a pan with 1 quart water, salt and pepper.", "Cook 20 minutes; add 1 cup milk. In a shaker, mix flour with other cup of milk.", "Add to soup. Stir constantly until it boils.", "Boil 1 minute.", "Add butter and parsley before serving.", "Add egg, if desired."]
["onion", "celery", "potatoes", "water", "salt", "pepper", "milk", "flour", "butter", "parsley", "egg"]