Boil the potatoes in salted water for about ten mins until tender.
Meanwhile blitz the red onion in a small food processor.
Drain the potatoes and allow to cool to room temp . Scatter in the red onion and snip the chives in with scissors. Add the mayo and yoghurt and then gently mix well together. Add a couple of pinches of salt. Taste and add more if required. Chill the ass off it.