Cover whole potatoes with cold water by 1 inch, add cooking salt and bring to a gentle simmer. Cook for 15 to 20 minutes until a knife enters easily, then drain and cool for 5 minutes.
Meanwhile, cook bacon in a large skillet over medium heat for 8 to 10 minutes until crisp. Transfer bacon to a plate and retain 2 tablespoons fat in the pan, discarding excess.
Cook onion in the retained fat for 4 minutes until soft. Add vinegar, broth, Dijon, sugar, dressing salt and pepper and simmer for 2 minutes, stirring to combine.
Cut warm potatoes into 1/4-inch rounds, halving large rounds if needed. Add them to the skillet with the bacon and fold gently over low heat for 2 minutes until coated.
Remove from the heat, rest for 5 minutes so the potatoes absorb some dressing and serve warm.