Preheat your oven to 375°F (190°C) to prepare it for baking.
Prepare the bell peppers by slicing off the tops and carefully removing the seeds and membranes. Keep the tops for later use if you like!
In a medium saucepan, combine the rinsed quinoa and vegetable broth. Bring to a vigorous boil over medium heat. Once boiling, reduce the heat to low, then cover and let it simmer for approximately 15 minutes, or until the quinoa has absorbed all the liquid and is fluffy.
In a large mixing bowl, combine the cooked quinoa, black beans, corn, and diced tomatoes. Add the cumin, chili powder, garlic powder, onion powder, and season with salt and pepper. Gently mix everything together until thoroughly combined.
Carefully fill each bell pepper with the quinoa mixture, packing it tightly to ensure they hold their shape.
Place the stuffed peppers upright in a baking dish. If they seem unstable, trim a small slice off the bottom to create a flat base.
Cover the baking dish with aluminum foil and bake in the preheated oven for 25 minutes to let the flavors meld.
After 25 minutes, remove the foil and generously sprinkle the shredded cheese over the top of each pepper. Return to the oven and bake for an additional 10 minutes, or until the cheese has melted and is bubbling with deliciousness.
Once baked, carefully take the peppers out of the oven and allow them to cool for a few minutes before serving.
Just before serving, adorn each stuffed pepper with diced avocado and a sprinkling of freshly chopped cilantro for an extra burst of flavor.
Notes
Serve the stuffed peppers on a colorful platter; you can place the tops of the peppers around the dish for an attractive display. Enjoy with a squeeze of lime for an added zesty touch!