Scrub the potatoes but don't peel them. Boil them in a large pot covered with an inch of water over high heat until tender, about 20 minutes depending on the size of the potatoes. Or use an Instant Pot: Place a trivet in the pot, add one cup of cold water, and place the potatoes on top of the trivet. Close the lid and cook at high pressure for 9-12 minutes depending on the size of the potatoes. Quick release the pressure.
While the potatoes are cooking, make the dressing. Cook the bacon in a medium skillet, stirring occasionally, until crispy. Take out the bacon and add the chopped onion to the pan. Cook onion until translucent but not browned. Add beef broth and bring to a simmer. Then turn down the heat and add vinegar, dijon mustard, oil, sugar, salt, and pepper.
Let the potatoes cool slightly so you can handle them.
Use a fork and a small knife and peel all the potatoes. Cut the potatoes into 1/4-inch slices or cubes and put them in a large bowl.
Pour the hot dressing over the potatoes. Mix the salad gently, fold in the bacon pieces and chopped chives. Let the salad rest for at least 20 minutes at room temperature before serving so that the potatoes can absorb the flavor of the dressing.
Serve warm or at room temperature! This salad keeps fresh for about 2 days in the fridge, let it come to room temperature for about 30 minutes before serving. The salad should not sit at room temperature for more than 2 hours.