Doctored with onion, chili powder and cocoa, canned sauce becomes a stepping-stone to something deeper.
Preheat oven to 400°. For sauce: In a medium saucepan, cook onion in 2 teaspoons hot oil over medium heat for 2 to 3 minutes or until just tender; add chili powder and cocoa, stirring to coat. Stir in enchilada sauce. Bring to boiling; reduce heat. Simmer, uncovered, for 10 minutes, stirring occasionally. Reduce heat to low, cover and keep warm.
For filling: In a medium saucepan, cover sweet potato with cold water. Bring to boiling; reduce heat. Simmer, uncovered, for 20 minutes or until tender when pierced with a fork, adding corn during the last 3 minutes of cooking. Drain well. Transfer to a large bowl; add beans. Slightly mash the mixture with a fork. Fold in the spinach, cilantro, cumin and garlic powder. Stir in 3/4 cup of the cheese.
Heat a medium skillet over medium heat; add enough oil to coat the bottom. Flash fry each tortilla until flexible, about 5 seconds per side, adding oil as necessary. Divide the filling among the tortillas. Roll up and place side by side, seam-side down, in a greased 2-quart rectangular baking dish.
Lightly brush the tops with 1/4 cup sauce. Bake, uncovered, for 20 to 25 minutes, or until heated through. Pour sauce over the enchiladas (how much depends on how saucy you like them) and bake for 5 minutes more. Top with remaining cheese and the green onions. Let stand 10 minutes before serving with sour cream.