Preheat the oven to 375°F (190°C).
Peel and dice the sweet potatoes into small cubes. Place them in a large pot of boiling water and cook for about 10–15 minutes until tender. Drain and set aside.
In a large mixing bowl, combine the cooked sweet potatoes, black beans, corn, cumin, chili powder, garlic powder, salt, and black pepper. Mix until well combined.
Lightly warm the corn tortillas in a frying pan over medium heat for about 30 seconds on each side to make them more pliable.
Spoon about ¼ cup of the sweet potato mixture onto each tortilla. Roll the tortillas tightly and place them seam-side down in a baking dish.
Pour the enchilada sauce evenly over the rolled tortillas, ensuring they are well covered.
Cover the baking dish with aluminum foil and bake in the preheated oven for 20 minutes.
Remove the foil and bake for an additional 10 minutes until the enchiladas are heated through and the sauce is bubbly.
Prepare avocado slices and chop cilantro for garnish while the enchiladas are baking.
Once done, remove the enchiladas from the oven. Serve warm, garnished with avocado slices, fresh cilantro, and lime wedges.