Place potato chunks in a large pot and cover with cold water by about 1 inch. Bring to a boil over high heat.
Once boiling, reduce heat to maintain a gentle simmer. Cook potatoes until just tender when pierced with a fork, about 15-18 minutes.
Drain potatoes in a colander and let them steam dry for 5 minutes—this helps prevent a watery salad.
While potatoes are still warm, transfer them to a large mixing bowl. Add mayonnaise, Dijon mustard, apple cider vinegar, salt, pepper, and paprika.
Gently fold everything together until potatoes are evenly coated with the dressing. Be careful not to mash the potatoes.
Stir in chopped red onion and parsley. If using bacon, sprinkle it over the top just before serving to keep it crisp.
Serve warm immediately, or let sit at room temperature for up to 30 minutes before serving.
