Put potatoes in a pot and cover with cold water by 1”.
Add salt and bring potatoes to a simmer.
Cook until potatoes are tender in the center.
Drain and remove from heat. Allow potatoes to cool at room temperature for 30-45 minutes.
While the potatoes are cooling, cook bacon on medium heat until the diced bacon is fully cooked and most of the fat has rendered.
Remove bacon from oil with a slotted spoon and reserve on paper towels to drain.
Cook onion on low heat in bacon fat.
Once the onion is translucent, add garlic and cook for an additional 3 minutes.
Remove from heat.
Add the apple cider vinegar, champagne vinegar, Dijon mustard, whole-grain mustard, and sugar.
Add the bacon and stir to combine.
Add the potatoes and fresh herbs and carefully stir to combine the mixture together.
Do not overmix the potatoes, as they fall apart easily after they are cooked.
Serve immediately, or cool in refrigerator and serve cold.