Place cubed potatoes in a large pot and cover with water. Bring to a boil over medium-high heat and boil for 15-20 minutes, or until tender. Drain and rinse in cold water until cool then place in a large mixing bowl; set aside.
Cut hardboiled eggs in half, remove the yolks and set aside in a separate mixing bowl. Coarsely chop egg whites then add to the large mixing bowl with the potatoes. Add celery and green onion to the bowl with the potatoes and stir to combine; set aside.
Mash the egg yolks with a fork, then add yogurt, mustard, relish, salt, and pepper and mix until combined. Add dressing to the other mixing bowl and stir until well combined.
Sprinkle paprika on top for garnish and refrigerate before serving.