Add coconut oil to a medium-sized pot over medium heat. Once the oil has melted, add onion, cumin, and garlic. Stir for about 3 minutes, then add black beans and broth.

Stir, cover, and simmer for about 10 minutes. Turn off the heat and use the back of a large spoon to mash the black beans to make it thicker. Alternatively, you can blend the soup in a food processor or blender. Mix in the cilantro before serving. Top with crushed corn chips, sliced avocado, and lime juice.