Preheat the oven to 400 degrees F and line a baking sheet with foil.
Rub the sweet potatoes with the olive oil and 1/4 teaspoon sea salt, then arrange on the baking sheet and bake 45-60 minutes or until tender.
Meanwhile, eat the 1 tablespoon olive oil in a large skillet over medium heat. Cook the onion until translucent, then stir in the garlic and saute for 30 seconds.
Add the beef and cook until there isn't any more pink on the meat. Add the remaining ingredients except avocado and green onions and simmer until the sauce thickens a little, about 5 minutes.
Slice each sweet potato in half and stuff with the taco filling. Serve garnished with avocado and green onion.