German Potato Salad

In a large pot over medium-high heat, bring the potatoes and enough water to cover to a boil and cook until just tender in the center, 20 to 40 minutes, depending on the size of your potatoes. To check if they are tender, poke them with the tip of a knife. It should slide in easily. Drain the potatoes and rinse them under cold water to cool them slightly. Peel them while they are still warm using your fingertips. The skins should slip right off. Slice them 1/8- to 1/4-inch (3- to 6-mm) thick and place them in a large bowl. (The thicker the slices, the less likely they are to crumble.)
While the potatoes are cooking, in a medium saucepan over medium heat, melt the butter. Add the bacon and onions and cook, stirring occasionally, until the bacon fat is rendered and onions are translucent, 7 to 9 minutes. Stir in the broth and bring to a simmer. Remove the saucepan from the heat and stir in the vinegar, mustard, salt, pepper, and celery seeds. Taste the dressing and add sugar or honey, if needed, stirring until completely combined.
Pour about 2/3 of the hot dressing over the sliced potatoes in the bowl and very gently stir to evenly coat the potatoes. Let the salad rest at room temperature for at least 30 minutes, occasionally stirring to coat.
Gently stir the potatoes again and taste to check the seasonings. If desired, add any more sugar or honey, salt, pepper, vinegar, or mustard, or add as much of the remaining dressing as you like. Sprinkle with the chives, if desired.