Slice bacon into roughly 1″ pieces, dice onion, mince garlic. Set aside.
In a small bowl, stir to combine vinegar, water and sugar. Set aside.
Fill a large pot with potatoes and fill with enough cold water to cover them. Add a pinch of salt and bring to a boil.
Once boiling, lower heat to medium high and let simmer for 15-20 minutes or until easily pierced with a fork. Drain, and return to stove top (without heat) and let sit while you prepare the rest of the ingredients.
In a separate large pot over medium heat, heat bacon until browned and crispy. Turn off heat and remove bacon from pot with slotted spoon and set aside in a bowl, leaving bacon grease in pan.
While grease cools a bit, cut potatoes into smaller chunks, roughly 1″ in size. Set aside.
Carefully add onions to pan and heat, stirring frequently, for a few minutes over medium heat. Add garlic and stir frequently for an additional minute.
Carefully add vinegar mixture, mustard, salt and pepper and stir to combine. Let simmer for a couple minutes then remove from heat.
Add diced potatoes and bacon into pan, and gently stir to combine. Add parsley and stir a couple times to combine.