Preheat the oven to 400 degrees. Peel the sweet potato and cut it into small 3/4 inch cubes. Toss the sweet potato cubes with olive oil, thyme, salt, and pepper. Spread the seasons sweet potatoes on a rimmed cookie sheet covered with aluminum foil. Roast the sweet potatoes in the preheated oven for about 35 minutes or until golden brown on the edges.