Step 1: Preheat your oven to 400°F (200°C). Toss the diced sweet potatoes with olive oil, cumin, and chili powder. Spread on a baking sheet and roast for 20-25 minutes until tender.
Step 2: While potatoes roast, sauté the onion and bell pepper in a skillet over medium heat until soft, about 5-7 minutes. Add the garlic and cook for another minute.
Step 3: In a large mixing bowl, combine the roasted sweet potatoes, sautéed vegetables, black beans, and corn. Stir in 1/4 cup of the enchilada sauce to coat the mixture.
Step 4: Reduce oven temperature to 375°F (190°C). Lightly grease a 9x13 inch baking dish and spread 1/2 cup of enchilada sauce on the bottom.
Step 5: Create a layer of tortillas over the sauce, followed by half of the sweet potato mixture and 1/2 cup of cheese. Repeat with another layer of tortillas, the remaining filling, and another 1/2 cup of cheese.
Step 6: Top with a final layer of tortillas, the remaining enchilada sauce, and the remaining cheese. Cover with foil and bake for 20 minutes.
Step 7: Remove the foil and bake for an additional 10-15 minutes until the cheese is bubbly and slightly browned. Let rest for 5 minutes before serving garnished with cilantro and lime.