In a 5- to 6-quart pan, add chicken broth, black beans, onion, and garlic. Bring to a boil over high heat. For a creamy soup, scoop about half the beans into a blender and whirl with some of the broth until puréed. Return to pan, add beef, and heat to simmering. Serve in bowls and add to taste cilantro, tortilla chips, and cotija cheese.