Preheat oven to 400.

Dice yellow onion.

Brown the ground beef with the diced onion.

Cut the tops off of the bell peppers - remove the seeds and and white parts.

Blanch the peppers for 15-20 minutes as the beef mixture cooks.

Add the black beans and corn to the ground beef mixture - drain. Mix in cilantro and green onions if desired.

Fill the peppers with beef mixture and place them in a roasting pan.

Cover and bake at 400 degrees for 45 minutes.

Once done cooking, add cheese and serve!