Preheat your oven to 400F/200C.

Wash the sweet potatoes and prick them several times with a fork. Place them on a lined baking sheet and bake for about 45–60 minutes, or until they're tender when pierced with a fork.

While the sweet potatoes are baking, heat olive oil in a skillet over medium heat. Add diced onions and cook until they're translucent, then add minced garlic and cook for another minute.

Add the ground beef to the skillet, breaking it up with a spatula. Cook until the beef is browned and cooked through.

Add the corn and beans. Season the beef mixture with chili powder, cumin, salt, and pepper. Stir well to combine, and let it simmer for a few minutes.

Once the sweet potatoes are done, remove them from the oven and let them cool slightly. Slice each sweet potato lengthwise and fluff up the insides with a fork.

Spoon the beef mixture over each sweet potato, dividing it equally among them.

Drizzle the sauce over each sweet potato. Garnish with chopped cilantro if desired, and serve hot.