Preheat the oven to 200c. Place the potatoes, 2 tbsp of the vinegar, and the salt in a large pot. Add water just to cover them. Bring to a boil, then reduce the heat to a simmer. Simmer for about 15 minutes, until the potatoes are tender when poked with a knife. Drain the potatoes and leave to cool.
Tip the potatoes onto a baking tray and gently smoosh them down with the base of a glass. Mix together the olive oil, garlic powder, garlic, and season with salt and pepper, and brush the mixture over the potatoes.
Roast the potatoes until light golden brown, 25-30 minutes. Remove from the oven, sprinkle on the Parmesan, and return to the oven for another 10 minutes, until the potatoes are crispy and golden.
Spoon the yoghurt onto a serving plate and then add the potatoes. Sprinkle with fresh herbs, Maldon sea salt and the remaining 1 tbsp vinegar.