Boil un-peeled potatoes in a saucepan until tender, about 40 minutes.

Fry bacon in a skillet until crisp, about 10 minutes.

Remove bacon and drain on paper towels.

Crumble the bacon and reserve.

Cook chopped onion in bacon drippings in the skillet until partially tender, about 5 minutes.

In a separate bowl, blend together sugar, flour, salt, pepper, water, and vinegar.

Add the blended mixture to the onion in the skillet.

Cook, stirring constantly, until the mixture thickens and bubbles, about 5 minutes.

Remove the skillet from heat.

Peel and slice the cooked potatoes.

Add the sliced potatoes to the onion mixture in the skillet.

Heat well, about 5 minutes.

Add sliced red radishes and toss to combine.

Serve hot, topped with crumbled bacon.