1Preheat your oven to 375°F (190°C).
Cut the tops off the bell peppers and remove the seeds and membranes.
In a large bowl, combine the cooked brown rice, black beans, corn, diced tomatoes, red onion, olive oil, and chili powder. Mix well.
Stuff each bell pepper with the rice and bean mixture.
Place the stuffed bell peppers in a baking dish.
Cover the dish with aluminum foil and bake for 30 minutes.
Remove the foil and bake for an additional 10-15 minutes, until the peppers are tender.
Remove from the oven and let cool slightly before serving.