Prepare Potatoes: Scrub the potatoes and chop them into bite-sized pieces. In a 2-quart pot, cover the potatoes with water. Bring to a boil, then lower the heat to medium-high. Simmer for 10 to 12 minutes or until fork-tender.
Cool Potatoes: Drain and transfer the potatoes to a bowl or plate. Cover them to keep warm. Clean the pot using a dish or paper towel.
Cook Bacon: In the same pot, cook the bacon pieces over medium heat until crisp, stirring occasionally. Remove the bacon with a slotted spoon and place it on a paper towel-lined plate.
Cook Onions: Add chopped onions to the pot with the remaining bacon drippings. Cook for 1 minute, stirring frequently.
Make Dressing: Remove the pot from heat. Gradually add vinegar, water, mustard, sugar, salt, and pepper, stirring well.
Simmer Dressing: Return the pot to the stove. Bring the mixture to a simmer, stirring for 1 minute.
Combine with Potatoes: Remove the pot from heat again. Add the potatoes, gently mixing until they've absorbed most of the liquid.
Add Bacon and Parsley: Stir in the cooked bacon and parsley.
Serve: Transfer the warm potato salad to a serving bowl and enjoy.
Notes
Start the potatoes in cold water to ensure they cook evenly.
Fry the bacon until crispy, adding both texture and necessary fat for the vinaigrette.
Adjust the sugar amount to suit your taste preferences.
Let the salad sit for a few minutes before serving to allow the flavors to meld.