Preheat the oven to 400F. Par boil the potatoes until just soft, drain and then smush with a glass. Mix the harissa and oil together and then pour this on top and mix. Roast in the oven for another 35-40 minutes until crisp around the edges.
Meanwhile, mix minced garlic with lemon juice and salt in a bowl, leave for 5 minutes and then stir through the yoghurt.
Spread it on a plate and top with the crispy pots, pickled onions and parsley
