Place your whole, unpeeled potatoes in a large pot and cover with salted water. Bring to a boil, then reduce to a simmer and cook for 25 to 30 minutes, until a fork slides in easily. Drain well and let them cool just enough to handle safely.
Once the potatoes are cool enough to touch, peel them if you like (I usually leave a bit of skin on for texture) and slice into rounds about a quarter-inch thick. Set them aside in a bowl while you work on the dressing.
In your large skillet, cook the bacon over medium heat until it's crisp and deeply golden. Remove it with a slotted spoon onto paper towels, but don't wash the pan you want those flavorful drippings left behind.
Add the chopped onion straight into the reserved bacon drippings. Cook it for a few minutes until softened and translucent, stirring so it doesn't catch or brown too fast.
Stir the flour, sugar, salt, celery seed, and pepper directly into the pan with the onions. This coats everything evenly and starts thickening the base before you add any liquid.
Pour in the water and cider vinegar, then cook while stirring constantly until the mixture thickens and starts to bubble. Let it bubble gently for another minute or two so the flour cooks off any raw taste.
Crumble the bacon back into the pan and add your sliced potatoes. Gently fold everything together and let it cook for about five minutes, just until heated through and every slice is coated.
Add the sliced hard-cooked eggs last, tossing very gently so they don't fall apart. Serve the salad warm, straight from the pan, for the most authentic experience.