Crispy Black Bean Sweet Potato Enchiladas

1. Preheat the oven to 425°F.
2. If using meat, cook in a skillet set over medium-high heat. Add the sweet potatoes and onions. Break up the meat as you go, about 5 minutes.
3. Add the taco seasoning and 1/2 cup water. Cook for 5 minutes, until fragrant. Mix in the salsa and black beans. Remove from the heat. 
4. Working in batches, warm the tortillas in the microwave in 30 second-intervals until pliable. Place the tortillas on a baking sheet and rub with olive oil on one side. Spoon 2 tablespoons of sweet potato mixture down the center of each tortilla. Roll up and arrange seam-side down on the baking sheet. 
5. Bake for 10 minutes, until crispy. Pour the enchilada sauce over the crispy enchiladas. Scatter the cheese all over the tortillas. Bake for another 10 minutes, until the cheese is melted and bubbling.
6. Top the enchiladas with avocado, yogurt, cilantro, lime juice, and sea salt.