Peel potatoes and cut into 1/2" dice. Cook in 2 1/2 cups water with the bay leaf, pepper and salt until half done. Heat lard, brown flour and onion until medium golden in color. Add 1/2 cup cold water and stir till smooth. Pour into the pot in which potatoes are cooking and cook over very low heat till potatoes are done. Stir every now and then. In a bowl mix well the sour cream, sugar, parsley and vinegar to taste. Pour into the potatoes, bring to a boil, and serve. Variation: substitute fresh marjoram for the parsley.
