1. Boil potatoes whole in salted water 15 min until fork‑tender; halve.

2. Cook bacon in skillet until crisp; remove, crumble. Reserve 2 Tbsp bacon fat.

3. Sauté onion in fat 2 min; whisk in vinegar, Dijon, sugar, pinch salt & pepper – this is the warm dressing.

4. Add potatoes to skillet; toss to coat, fold in bacon and parsley. Serve warm.