Dice the bacon.

Chop the onion.

Cook bacon in a large skillet until crisp.

Drain off most of the bacon fat, leaving about 1/4 cup in the skillet.

Add the chopped onion to the skillet and cook for 1 minute, until softened.

Blend in the flour, stirring until smooth.

Stir in the water and cider vinegar gradually.

Cook, stirring constantly, until the mixture thickens and becomes bubbly.

Stir in the sugar, salt, and pepper until dissolved.

Gently fold in the cubed cooked potatoes into the dressing.

Heat through and serve warm.