Wash and cut potatoes into 3/4 inch pieces
Cover potatoes with water in a medium saucepan; season with salt, and bring to a boil.
Reduce heat and simmer until tender, 10 to 12 minutes.
Drain. Reserving 1 tablespoon cooking liquid. Let cool
Whisk together vinegar, mustard, and reserved cooking liquid. Add oil in a slow, steady stream, whisking constantly until emulsified.
Transfer potatoes to a bowl, and drizzle with vinaigrette.
Gently stir in goat cheese, celery, shallot, and parsley. Season with salt and pepper.