Combine the beans, water, cumin, salt and pepper in a pot over medium high heat. Lightly boil for 5 to 10 minutes until the liquid reduces and the mixture can be mashed into a paste (using a potato masher or back of a fork).
Meanwhile, slice the peppers in half, remove the seeds and ribs, and place cut side up on a baking sheet lined with foil or parchment paper.
Fill each pepper with a spoonful of the bean mixture, top with cheese, and bake until golden brown, 20 to 22 minutes. Top with sour cream and cilantro and serve.