Preheat oven to 375°F.
Scrub sweet potatoes and cut in half length wise.
Put the potatoes cut side down on a non-stick baking sheet and bake for 20-30 minutes, or until tender.
Remove pulp from potatoes, put into a bowl and mash.
Add chili powder, cumin, and salt & pepper.
Heat a flat skillet on medium heat. Place one tortilla on the skillet and cook for a short time.
Add sweet potato mixture and 2 tablespoons of black beans.
Top with peppers, lettuce, and onions as desired.
Add another tortilla with sweet potatoes spread on the bottom, and place it on the first tortilla.
When the first tortilla is brown, use two spatulas to flip to 2nd side.
Cook until light brown on both sides.
Add avocado to the top or inside the tortillas and enjoy!