Peel and cube the potatoes into cubes (about 2cm size each).
Place potatoes into a large saucepan. Cover with water, add salt. Bring to a boil then reduce the heat to a simmer. Cook the potatoes until slightly tender but not falling apart for about 10 minutes. Drain using a colander and transfer to a large mixing bowl.
In a small Pyrex bowl combine the yogurt, mayonnaise, mustard, and vinegar. Season to taste with the salt and pepper. Add to the potatoes and gently stir to combine.
Add the celery, red onion, and chives to the potato mixture, stir to combine. Check seasoning. Add more salt and pepper to taste if required.
Cover and refrigerate for about 1 hour before serving to allow the salad to marinate and chill.