Bring a large pot of salted water to a boil.
Add the potatoes and cook until fork tender, about 15–20 minutes. Be careful not to overcook them, as you want the potatoes to hold their shape.
Drain the potatoes and allow them to cool slightly.
While the potatoes are cooling, finely chop the parsley, slice the green onions, and mince the garlic.
Place the warm potatoes in a large mixing bowl.
Add the parsley, green onions, garlic, olive oil, vinegar, and salt.
Gently toss everything together until the potatoes are evenly coated with the dressing and herbs.
Taste and adjust the salt or vinegar as needed.
Cover and refrigerate for at least 1 hour before serving.
Serve chilled or at room temperature.