Cover whole potatoes with cold water by 1 inch; add cooking salt. Gently simmer 15 to 20 minutes until easily pierced. Drain; cool 5 minutes.
Meanwhile, cook bacon in a large skillet over medium 8 to 10 minutes until crisp. Transfer to plate; retain 2 tablespoons fat and discard excess.
Cook onion in fat 4 minutes until soft. Add vinegar, broth, Dijon, sugar, dressing salt, and pepper; simmer 2 minutes, stirring.
Slice warm potatoes into 1/4-inch rounds, halving large ones. Add with bacon; gently fold over low 2 minutes to coat.
Remove from heat; rest 5 minutes to absorb dressing. Serve warm.