Boil potatoes in a large pan with 1 tablespoon salt until fork tender.
Drain and run under cold water. Cut potatoes into half or quarters and add to large bowl.
Meanwhile, in a heavy skillet, cook bacon until crispy about 8-10 minutes.
Remove bacon from pan and place on plate lined with paper towels, set aside.
Add onions to skillet and cook about 5 minutes or until tender.
Drain grease off of onions and add to a large bowl with the potatoes. Chop bacon into small pieces and add to bowl. Gently stir to combine.
In a small bowl, whisk together white vinegar, mustard, 1 teaspoon salt and pepper.
Pour over potatoes in large bowl and stir to combine.
Serve immediately or room temperature.
Store leftovers in refrigerator.