Preheat the oven to 200˚C.
Place the potatoes in a pot, fill it with enough cold water to cover the potatoes by a couple of centimetres, and add the salt.
Bring the water to the boil, then lower it to a simmer until the potatoes are soft, about 30 minutes.
Drain the potatoes, allow them to cool slightly, then transfer them onto a baking tray. Using a potato masher or spatula, gently smash the potatoes to about 1cm height.
Roast the potatoes in the oven until they are golden brown, about 30 minutes. Transfer them to a plate, drizzle them with the chilli oil and top with the coriander and spring onions.