Preheat oven to 425 degrees. Cook rice according to package instructions. Prepare bell peppers by slicing them in half from top-to-bottom (some people slice off the top instead, but we prefer this method since it allows for more surface area for melted cheese on top) and removing seeds with a knife. Place them on a foil-lined baking sheet skin-side down and bake them without anything in them for 15 minutes.
Meanwhile, prepare the rest of the ingredients. On the stove, cook the ground meat in a large pan, using a spatula to break it into small chunks as it cooks- it is ready when you no longer see pink and the meat starts to crisp. In a different pan, you can simultaneously sauté the onion, adding garlic and serrano pepper when the onions start to turn golden.
When the meat is ready, you can add the garlic/onion/serrano pepper to the meat pan and add the cooked rice, fire-roasted tomatoes, corn, and black beans. Add the spices to the filling and mix everything thoroughly.
Next, spoon the filling into the bell peppers. Turn the oven down to 350 degrees and bake for ~25 minutes, then top with cheese, and put back in oven for another 10 minutes or until cheese is fully melted.
Notes
You can serve with salsa, guacamole, and/or sour cream.