Preheat oven to 425°F. Add peeled and cut sweet potatoes to a medium sheet pan. Drizzle with 1 - 1½ tablespoon oil, season, then use hands or stir to coat well.
Bake until fork tender, while stirring halfway through, about 25-30 minutes. For crispy tops and edges, broil the last few minutes. Reduce oven to 400° F.
Enchilada Sauce
Meanwhile, heat 1 tablespoon oil in a medium skillet over medium high. Once heated, add garlic and stir for 30 seconds, then add onions and a generous dash of salt. Cook until softened, about 3-5 minutes. Add to a medium bowl and set aside. To the skillet, add the green enchilada sauce and green chiles. Let simmer, stirring every so often.
To the onions and garlic, scoop the flesh of the avocado and smash lightly with a fork. Add the sweet potatoes, black beans, cilantro/green onions, cumin, chili powder, garlic powder and salt. Mix. If necessary, adjust seasoning to taste.
Add 1/3 to 1/2 cup enchilada sauce to the bottom of a medium size baking dish. Add a light coat of sauce to the outside of each tortilla, then line the center of each tortilla with about 1/3 to 1/2 cup sweet potato/black bean filling. Add maybe a tablespoon of cheese, then roll tight and place in the dish, seam side down. Repeat until the filling is gone and the dish is full. Cover evenly with remaining sauce, then sprinkle with cheese, cilantro or green onions.
Bake 15-20 minutes or until the cheese is melted and the sauce edges are bubbling. If wanting a crisp top, broil for a few minutes past finished.
Top with fresh chopped lettuce (dried well) extra black beans, avocado, green onions, cilantro, bell peppers, tomatoes, hot sauce, or lime. Enjoy every flavor filled bite.