Pre-heat the oven to 180ºC.
Cut a slit through the skin along the length of each sweet potato and place on a baking tray.
Place in the preheated oven for 45 - 50 minutes or until tender when a sharp knife is inserted.
Squeeze the cooked sweet potatoes to open them up and place on a serving plate.
Sprinkle crumbled feta over each sweet potato, then drizzle each one with 1/2 tsp of harissa paste.
Sprinkle the chopped spring onion over each sweet potato and serve.