1 teaspoon salt
2-1/2 pounds small Yukon Gold potatoes, unpeeled
3 celery stalks, cut into slices ¼ inch thick
¼ cup finely diced red onion

Dressing:
1/2 cup sour cream
½ cup mayonnaise
1 tablespoon mustard seeds
1 green onion, including the tender green tops, finely chopped
¼ cup finely chopped fresh parsley
1 teaspoon dry mustard
¼ teaspoon salt
1/8 teaspoon freshly ground pepper
1 tablespoon finely chopped fresh parsley

Bring a large saucepan three-fourths full of water to a boil. Add the salt and then the potatoes. Broil until tender but slightly resistant when pierced with a fork, 15-25 minutes depending on the size. Drain, and, when cool enough to handle, cut the unpeeled potatoes into 1-inch pieces.



In a bowl, combine the potatoes, celery and red onion and toss briefly to mix. Set aside.



To make the dressing, in a small bowl and using a fork, stir together the sour cream, mayonnaise, mustard seeds, green onion, parsley, dry mustard, salt and pepper, mixing well.



Pour the dressing over the potato mixture. Using a large spoon, mix well, being careful not to break up the potatoes too much.



Transfer the salad to a large serving platter or bowl, if desired. For the best flavor, cover and chill for up to 2 hours before serving. Sprinkle the parsley over the top and serve.