Preheat oven to 180˚C. Wash the sweet potatoes and cut off a small sliver on the bottom of the potato to give it a stable surface. Cut the sweet potato into rough 1/2cm slices, leaving the bottom in tact. (You can do this by sight/feel, or by placing chopsticks on either side of the potato and slicing until you hit the chopsticks).
Place in a roasting pan. Spread the Flora over each potato and in between the slices then sprinkle with salt and pepper. Roast in the oven until the sweet potatoes are soft in the middle and easily pierced with a paring knife, 45 to 55 minutes depending on the size of your sweet potatoes.
Mix the sour cream and harissa together and season well. Serve the hot sweet potatoes with the spiced sour cream and fresh coriander on the side.