Instructions

1. Adjust oven rack to upper-middle position and preheat oven to 425°F. On a large rimmed baking sheet, toss sweet potato, poblanos, and onion with ¾ teaspoon salt, 2 tablespoons olive oil, 1 teaspoon chili powder, 1 teaspoon cumin, and ½ teaspoon garlic powder until evenly coated. Bake until tender and browned, about 20 minutes.

2. While the vegetables roast, make the enchilada sauce: In a medium saucepan, heat the remaining 2 tablespoons oil over medium heat until shimmering. Add tomato paste, 1 tablespoon minced chipotles in adobo, 1 teaspoon oregano, remaining 2 tablespoons chili powder, remaining 1 tablespoon cumin, and remaining 1 teaspoon garlic powder. Cook, stirring constantly, until fragrant, about 1 minute. Whisk in broth and bring to a boil over medium-high heat. Reduce to a simmer over medium-low and cook, whisking occasionally, until slightly thickened and reduced to about 3½ cups, 15 to 20 minutes.

3. Transfer roasted vegetables to a large bowl. Stir in black beans, ½ cup sour cream, and 1 cup shredded cheese until evenly distributed. Reduce oven temperature to 375°F.

4. Pour ¾ cup enchilada sauce into a 9×13-inch baking dish and tilt to coat the bottom. Pour 1 cup sauce into a shallow dish. Working one at a time, dip each tortilla into the sauce until lightly coated on both sides. Lay flat on a parchment-lined surface, place a scant ¼ cup filling in a line down the center, roll up tightly, and set seam side down crosswise in the baking dish. Repeat until all tortillas and filling are used; the dish will be tightly packed.

5. Pour remaining 1¾ cups sauce over the enchiladas. Sprinkle remaining 1 cup cheese down the center. Cover tightly with foil and bake until cheese is melted and sauce is bubbly, 25 to 30 minutes.

6. Remove foil and broil on high until cheese is browned, 4 to 5 minutes. Let sit 5 minutes, then serve hot sprinkled with cilantro and dolloped with additional sour cream.

Notes:

Kosher salt: This recipe is calibrated for Diamond Crystal kosher salt. If using table salt, use half the volume or the same weight.

Chipotle chiles in adobo: One tablespoon of minced chipotles gives moderate heat and smokiness. Use less for a milder dish; the remainder freezes well portioned into tablespoon-sized amounts.

Tortilla dipping: Coating each tortilla in sauce before rolling prevents them from drying out during baking and helps them hold their shape. Warming the tortillas first makes them pliable and less likely to crack.

Cheese: Shredding from a block melts more evenly than pre-shredded. Pepper Jack can substitute for more heat; a mild white cheddar also works.

Do Ahead: Assemble the enchiladas through step 5, cover, and refrigerate up to 24 hours before baking. Add 10 minutes to the covered bake time if going straight from the fridge.