Cut the tops off the bell peppers and remove the seeds and membranes. Set aside.
In a medium saucepan, combine the quinoa and vegetable broth. Bring to a boil over medium heat. Once boiling, reduce the heat to low, cover, and simmer for about 15 minutes or until the quinoa is fluffy and the liquid has been absorbed.
In a large mixing bowl, combine the cooked quinoa, black beans, corn, diced tomatoes, cumin, chili powder, garlic powder, onion powder, salt, and pepper. Mix until well combined.
Carefully spoon the quinoa mixture into each bell pepper, packing them tightly.
Place the stuffed peppers upright in a baking dish. If they wobble, you can slice a bit off the bottom to stabilize them.
Cover the baking dish with foil and bake for 25 minutes.
Remove the foil and sprinkle shredded cheese on top of each pepper. Return to the oven and bake for an additional 10 minutes, or until the cheese is melted and bubbly.
Once done, remove from the oven and let cool for a few minutes.
Garnish each stuffed pepper with diced avocado and chopped cilantro before serving.
Notes
Feel free to customize the toppings and spices according to your taste.