In a nonstick skillet, cook cumin and garlic in olive oil over medium heat until you can smell it. Add beans, tomato juice, and salt. Continue to stir until it is heated through. Add corn- if you choose. Stir in cilantro just before serving.
(I had somehow thought this didn't need to be cooked when I started putting it together. So I ended up just mixing everything together and then cooking it a bit. It was good but I found that there was a lot of tomato juice. I don't know if that would still be the case if you did it according to the actual directions.)
Recipe by Talking in ALL CAPS at https://talkinginallcaps.com/2013/04/books-and-bites-cafe-rio-and-419.html