Boil the red potatoes until they are cooked through but still firm.

Let the potatoes cool down until they are easy to handle.

Slice the cooled potatoes into thick slices.

Dice the onions into small pieces.

Dice the celery into fine pieces.

Dice the green pepper into small pieces.

Hard boil eggs, then dice 2 eggs.

Fry the bacon until it is crispy.

Reserve the bacon and bacon grease.

Combine sliced potatoes, diced onions, diced celery, diced green pepper, diced eggs, salt, pepper, and celery seed in a large bowl.

Pour the bacon and bacon grease over the potato mixture.

In the skillet used for frying bacon, add cider vinegar, water, and sugar.

Bring the mixture to a boil.

Create a thickening agent by mixing flour and water.

Slowly add the flour and water mixture to the boiling vinegar mixture, stirring constantly, until it thickens to a gravy-like consistency.

Pour the thickened vinegar mixture over the potato mixture and toss well to combine.

Let the potato salad stand for at least 2 hours to allow the flavors to meld.

Taste the potato salad and adjust the seasoning as needed, adding more vinegar, water, and sugar to achieve the desired tartness.

Dice the remaining 2 hard boiled eggs for garnish.