Polish Potato Casserole
["1 Tbsp. butter or margarine", "2 Tbsp. all-purpose flour", "2 c. skim or low-fat milk", "1/4 to 1/2 tsp. salt (if desired)", "1/4 tsp. freshly ground pepper", "4 large potatoes (about 2 lb.), peeled and sliced thin", "1 large onion, sliced thin", "1/2 lb. green cabbage, shredded (2 c.) or more if desired", "1/2 lb. kielbasa, sliced thin"]
["In medium saucepan, melt the butter or margarine; stir in flour.", "Cook, stirring, for 1 minute, then gradually add the milk, stirring constantly to eliminate lumps.", "Cook the mixture over moderately low heat, stirring it, until the sauce begins to thicken.", "Stir in the salt and pepper.", "Set the sauce aside."]
["butter", "flour", "milk", "salt", "freshly ground pepper", "potatoes", "onion", "green cabbage", "kielbasa"]