Sweet Potato-Black Bean Enchiladas

2 sweet potatoes, peeled and cut into 1/2-inch cubes

1 white onion, diced

4 tablespoons olive oil, or as needed

1 teaspoon chili powder

1 teaspoon oregano 

1/2 teaspoon cumin

1 (15-ounce) can black beans, drained and rinsed

1 (4-ounce) can diced green chiles

16 ounces Oaxaca or Monterey Jack cheese, shredded

8 ounces sour cream

1 1/2 cups red enchilada sauce

14 corn tortillas

Salt, to taste

Heat oven to 400° F. Line a sheet pan with parchment paper. 

In a mixing bowl, toss together sweet potatoes and onion with 2 tablespoons oil. Season with chili powder, oregano, cumin and salt to taste. Spread into an even layer on prepared pan and roast until tender and browned, about 35 minutes. Let stand until cool enough to handle. Reduce oven temperature to 375° F.

Transfer potato mixture to a clean mixing bowl. Stir in beans, chiles, 1 cup cheese and 1/2 cup sour cream. Season lightly with salt and set aside.

In a small skillet, heat just enough oil to coat the bottom of the pan. Working one at a time, toast tortillas until soft and pliable, about 30 seconds per side, adding oil to pan as needed. 

Cover the bottom of a 9×13-inch baking dish with a thin layer of enchilada sauce (about 1/2 cup). Lay a tortilla on a work surface. Add about 1/4 cup potato mixture and roll up. Place in dish on top of enchilada sauce. Repeat with remaining tortillas and filling. 

Pour remaining enchilada sauce over rolled tortillas, then top with remaining cheese. Cover dish with foil. Bake until cheese is melted, about 25 minutes. Remove foil and bake 10 minutes longer, or until cheese is lightly browned. Let stand for 5 minutes, then serve with remaining sour cream.