Scrub sweet potatoes with a brush to clean. Cook whole sweet potatoes in an oven heated to 400°F for 45 minutes.
Meanwhile, cut the onion into a large pan with olive oil over medium heat. When onion begins to brown, add the tofu, chili powder, and garlic powder. Cook for 10 minutes, stirring occasionally. Remove from heat and add black olives.
When the potatoes are cooked, cut them gently in half lengthways. Let them cool a little and press the flesh down with a fork.