1. Preheat the oven to 200°C (400°F).
Cut the sweet potato in half lengthwise and place the flesh side down on a baking sheet lined with parchment paper.
Bake for 45 minutes to 1 hour. Pierce the flesh of the sweet potato to check for doneness, it should be tender.
Meanwhile, peel and finely slice the onion. Roughly chop the raw chicken.
Heat a drizzle of olive oil in a sauté pan and sauté the onion for a few minutes. Add the chicken and lightly brown it. Add the tomato sauce, salt, and pepper, then mix well.
Scoop out the flesh of the sweet potatoes without damaging the skin, mash it with a fork, and mix it with the previous mixture.
Fill the sweet potato skins with this stuffing, then sprinkle with a little grated cheddar cheese and oregano.
Broil for a few minutes to brown the top. Serve with a nice salad or green vegetable.