Bring a large pot of water to a boil. Add potatoes when it reaches a rolling boil. Boil potatoes for 12-15 minutes, until easily pierced with a fork. (You will be adding the corn for the last minute of boiling)
Meanwhile, chop celery and slice the green onion and set aside
In a medium sized mixing bowl, combine all dressing ingredients, mix with a fork until well combined.
Once potatoes are done, remove from heat and add to a strainer. Run cold water over them until they are cool enough to handle.
Quarter potatoes or cut smaller if desired. Add potatoes, corn, feta cheese, celery and green onion to the bowl with the dressing, mix with a fork to evenly cover all ingredients. Some of the potatoes will break up even more, this is ok, it will give it a nice creamy texture.
Serve warm or refrigerate for a cold potato salad.