Step 1

Preheat oven to 425 degrees F.

Step 2

Heat oil in a large cast-iron skillet over medium-high heat. Add sweet potatoes and 1/4 teaspoon salt. Cook, stirring occasionally, until beginning to brown, 5 to 7 minutes. Transfer the pan to the oven and bake until the sweet potatoes are soft, 15 to 20 minutes.

Step 3

Meanwhile, combine sour cream, lime juice and the remaining pinch of salt in a small bowl.

Step 4

Top the sweet potatoes with corn, cheese and beans. Continue baking until the cheese is melted, about 5 minutes. Top with tomatoes, scallions and avocado. Drizzle with the sour cream mixture. Serve topped with cilantro (if using).