Potato Soup
["8 medium potatoes, peeled and sliced", "2 qt. water", "1 onion, chopped", "6 Tbsp. butter or margarine", "6 Tbsp. flour", "1 tsp. salt", "1 tsp. pepper", "1 1/2 c. milk"]
["In large pot, cook potatoes in water until tender, about 20 minutes.", "Drain, reserving liquid.", "Set potatoes aside."]
["potatoes", "water", "onion", "butter", "flour", "salt", "pepper", "milk"]