Cook the potatoes in salted boiling water until barely tender when pierced with a fork, about 20 minutes.
Gently drain the potatoes and spread them on a paper-towel line baking sheet to drain more and cool slightly.
Toss the potatoes to the bowl with rice vinegar and salt and let stand.
Make the dressing: In a glass measuring cup, whisk together the vinegar, mustard, salt, and pepper. Slowly whisk in the oil until blended.
Gently fold the scallions, pickles, and parsley into the potatoes. Whisk the vinaigrette and fold enough of it into the potatoes to generously coat them
Serve while still slightly warm, topped with the crumbled bacon.