In a medium saucepan, bring 2 cups of vegetable broth to a boil. Add the quinoa, reduce heat to low, cover, and let it simmer for about 15 minutes, or until all the liquid is absorbed.
Slice the tops off the bell peppers and remove the seeds and membranes. Place them upright in a baking dish.
In a large skillet over medium heat, sauté the chopped onion and minced garlic until the onion is translucent, about 3-4 minutes.
Add the cooked quinoa, black beans, corn, diced tomatoes, cumin, smoked paprika, chili powder, salt, and pepper to the skillet. Stir well to combine all the ingredients and cook for an additional 5 minutes until heated thoroughly.
Spoon the quinoa mixture into each bell pepper, packing it down slightly. Fill them generously and place any extra mixture around the peppers in the dish for added flavor.
Cover the baking dish with aluminum foil and bake in the preheated oven for 25-30 minutes, until the peppers are tender.
Remove the foil and bake for an additional 10 minutes for a lovely roasted finish.
Once done, allow them to cool for a few minutes. Garnish with fresh cilantro and serve with slices of avocado on the side.
Notes
Feel free to customize the filling with your favorite vegetables.