Hot German Potato Salad

2 pounds potatoes
1 teaspoon salt
1/8 teaspoon pepper
1 teaspoon dry mustard
1/2 teaspoon granulated sugar
1/2 teaspoon flour
1/2 cup water
1/2 cup vinegar
1/4 pound bacon or 2 tablespoons butter
1 medium onion, finely chopped

Cook potatoes in boiling salted water until tender. drain, peel, and while hot, cut into 1/8-inch slices; sprinkle with the salt, pepper, mustard, sugar and flour. Heat water and vinegar to boiling point. Place bacon or beef, sliced and chopped fine, in skillet. Fry until light brown. Add onions. Brown slightly. Add potatoes and the hot vinegar; heat through to absorb the vinegar and water; serve warm.

NOTE: If butter is used, the bits of fried bacon may be omitted. If the salad is too dry, add a little hot water. It should have a glassy look without being lumpy or greasy.