Boil the potatoes for 15 mins or until, tender, then drain and cool. Stir together the garlic, yogurt, vinegar and sugar with
some seasoning, to make the dressing. Can be made to this stage up to a day ahead.
To serve, mix most of the spring onions and mint into the dressing, then pour it over the potatoes. Stir gently, taking care not to break the potatoes up. Scatter with the rest of the spring onions and mint to serve.