Cook 7 to 8 potatoes to fork tender. Peel and slice. Cut up 4 or 5 slices bacon into little squares; fry brown. Take bacon bits out of pan and put on potatoes. Chop onion and put into grease. Fry slow. Add 2 tablespoons flour; stir well. Add 1/4 cup vinegar, salt and pepper, 1/2 cup sugar and water for right consistency. Simmer a few minutes and put over potatoes. Mix gently.