Vegetable oil, for the rack
6 large sweet potatoes or yams
Butter and brown sugar, for serving
1. Position the grill rack 4 inches from the heat source, brush with vegetable oil, and preheat to high.
2. Use tongs to carefully lay the potatoes on the hot embers. Roast the potatoes, turning occasionally with the tongs, until the skins are black and the potatoes are fork tender, about 40 minutes to 1 hour.
3. Remove from the barbecue, and serve immediately with butter and brown sugar on the side.