Place potato chunks in a large pot and cover with cold water by about 1 inch. Add 1 teaspoon salt to the water.
Bring to a boil over high heat, then reduce to a simmer. Cook until potatoes are tender when pierced with a fork, about 10-12 minutes.
While potatoes cook, make the dressing. In a medium bowl, whisk together mayonnaise, Dijon mustard, whole grain mustard, apple cider vinegar, honey, salt, and pepper until smooth.
Drain potatoes well and transfer to a large mixing bowl. Let cool for 5 minutes—they should still be warm but not hot.
Add red onion and celery to the potatoes. Pour dressing over everything and gently fold together until evenly coated.
Fold in parsley, dill, and chives. Taste and adjust seasoning with more salt or pepper if needed.
Serve immediately or cover and refrigerate until ready to serve. The flavors will develop as it sits.