Combine all the sauce ingredients in a blender and blend until very smooth.
Transfer the sauce to a small pot and cook on low for 5 minutes or so, just until it's thickened somewhat. Keep whisking the sauce continuously for about 5 minutes. Let cool off/ It will thicken more as it cools. Can be made ahead and stored in the fridge for up to 4 days.
In a mixing bowl, combine the ingredients for bowls, except for rice. Stir to mix well.
Layer brown rice and the black bean mixture in serving bowls. Drizzle with the cheesy sauce. Heat up in the microwave and serve.