To the potatoes, add the reserved egg whites and any leftover deviled egg filling, green onions, celery, mayonnaise, mustard, celery seed, salt, pepper, garlic powder, and chopped pickles and pickle juice, if using. Stir to combine, then taste and add more salt, if needed.
1 bunch green onions, 2 stalks celery, 1 1/2 cups mayonnaise, 1/4 cup yellow mustard, 1 1/2 teaspoons celery seed, 1/2 teaspoon salt, 1/2 teaspoon pepper, Pinch of garlic powder, 1/4 cup chopped dill pickle, 2 Tablespoons pickle juice