Step 1

Make the sauce: Heat the oil in a large skillet over medium heat until shimmering. Add the onion and cook, stirring occasionally, until soft and fragrant, about 5 minutes. Add the flour, stir to coat the onions, and cook for 2 minutes to lightly toast the flour.

Step 2

Stir in the chili powder, tomato paste, garlic powder, cumin, oregano, salt, cayenne, and black pepper. Cook until fragrant, about 1 minute. Gradually whisk in the broth. Bring the sauce to a boil, then reduce the heat and simmer until thickened, 6 to 8 minutes. Remove the pan from the heat.

Step 3

Make the enchiladas: Arrange a rack in the middle of the oven and heat to 425°F.

Step 4

Toss the squash with the olive oil and salt, and arrange in a single layer on a rimmed baking sheet. Roast until tender and caramelized, 20 to 25 minutes, stirring once halfway through. Cool slightly. Reduce the oven temperature to 350°F.

Step 5

Place the roasted squash, black beans, and corn in a large bowl, and stir to combine. Spread 1/2 cup of the sauce in an even layer over the bottom of a 9x13-inch baking dish.

Step 6

To assemble the enchiladas, place the tortillas on a flat work surface. Spread about 2 tablespoons of sauce over the top of each tortilla, then top with 1/2 cup of the vegetable mixture and about 2 tablespoons of cheese. Roll tightly to close, and place seam-side down in the baking dish. Repeat with the remaining tortillas. Spread the remaining sauce over the top of the enchiladas, then sprinkle with the remaining cheese.

Step 7

Bake, uncovered, for 20 minutes. Meanwhile, place the greens, sliced red onion, cilantro, and lime juice in a medium bowl and toss to combine.

Step 8

Divide the enchiladas between plates, top with greens, and serve.