Preheat the oven to 350°F.
Wash and dry the sweet potatoes. Wrap each potato in aluminum foil and roast in the oven until easily pierced with a knife, about 45 minutes – 1 hour. (The timing will depend on how large your potatoes are). Remove from the oven and allow to cool for a couple of minutes in the foil.
Remove the potatoes from the foil and halve the potatoes lengthwise. Top each half with the yoghurt, feta, arugula, chopped pecans and black pepper. Serve while still very warm.