Preheat the oven to 375 degrees and lightly grease a 9x9 baking dish.
Heat olive oil in a large skillet over medium heat. Add the diced sweet potatoes and onion. Cook for 8 minutes, stirring now and then, until the potatoes start to soften.
Stir in the garlic, cumin, chili powder, salt, and pepper. Cook for 1 minute until fragrant.
Add the black beans and salsa to the skillet. Stir everything together and remove from heat.
Spread half the torn tortillas in the bottom of the baking dish. Top with half the sweet potato mixture and half the cheese. Repeat the layers once more.
Bake uncovered for 20 minutes until the cheese melts and the edges turn golden.
Remove from the oven and let it rest for 5 minutes. Sprinkle with chopped cilantro before serving.