Preheat the oven to 375°F.
Cut the tops off the bell peppers and remove the seeds and membranes.
In a large bowl, combine cooked quinoa, olive oil, diced onion, minced garlic, black beans, corn, Italian tomato sauce, and shredded cheese.
Mix all the ingredients well.
Stuff the bell peppers with the quinoa mixture and place them in a baking dish.
Bake in the preheated oven for about 25-30 minutes or until the peppers are tender.
Serve and enjoy!