Preheat the oven to 375°F and lightly grease a 9x13 baking dish.
Heat a skillet over medium heat and cook the onion and garlic until soft, about 4 minutes.
Stir in the black beans, cumin, chili powder, and salt. Cook for 3 minutes, then remove from heat.
Warm the tortillas briefly so they are flexible. Spoon the bean mixture down the center of each tortilla, add a little cheese, and roll them up.
Place the rolled tortillas seam side down in the baking dish. Pour the enchilada sauce evenly over the top and sprinkle with the remaining cheese.
Bake for 20 minutes until the cheese is melted and bubbly.
Let the enchiladas cool for 5 minutes. Place the sour cream in a small zip bag, snip off one corner, and pipe circles across the top. Drag a knife through the circles to form a web pattern.
Sprinkle with cilantro before serving.