Bake the sweet potatoes. Preheat to 400 º. Line a rimmed baking sheet with parchment paper for easy cleanup. Scrub the sweet potatoes to clean and pat dry. Prick the outsides all over with a fork. Rub them in oil and sprinkle a pinch of salt and pepper over them.
Place on the prepared baking sheet and bake until fork tender, about 35-40 minutes, longer depending on size. Remove from the oven and let rest until cool enough to handle. Leave the oven turned on.
Meanwhile, cook the ground beef mix in a large skillet. Add the beef to a heated skillet over medium heat. Chop the meat up with a spatula for about 3 minutes. Add in chopped onion, bell pepper, garlic. Continue to cook for about 4 minutes, soak up any excess grease with paper towels in the skillet, discard the paper towels.
Add in the seasonings, mix well. Cook for another 3-4 minutes. Add in green chilies, taco sauce and sour cream (if using). Take it off the heat. Set aside.
Stuff the sweet potatoes. Once the baked sweet potatoes are finished and cool enough to handle, make a slit in the top. With a fork, open the split and lightly fluff the insides to make space for the toppings. Place the sweet potatoes back on the baking sheet, then over stuff with the beef mixture. Sprinkle cheese over the top, then return the sweet potatoes to the oven to melt and heat the filling a bit. Cook for about 5 minutes.
Pull from the oven and top with additional toppings of choice. Optional: extra sour cream, avocado sliced or smashed into guac, cilantro, salsa and so on. enjoy!