Prepare the bell peppers by cutting the tops off and carefully removing the seeds and membranes inside. Lightly season the insides with salt and pepper, then place them upright in a baking dish, ensuring they are snug.
In a medium saucepan, combine the rinsed quinoa and vegetable broth. Bring this mixture to a boil over medium-high heat. Once boiling, reduce the heat to low, cover the saucepan, and let it simmer for approximately 15 minutes or until the quinoa has absorbed all the liquid and is fluffy.
While the quinoa is cooking, heat a splash of olive oil in a large skillet over medium heat. Add the diced red onion and sauté for about 3-4 minutes or until it becomes softened. Stir in the minced garlic, ground cumin, chili powder, and smoked paprika. Cook for an additional minute, allowing the spices to toast and become fragrant.
In a large mixing bowl, combine the cooked quinoa, the sautéed onion mixture, black beans, corn, halved cherry tomatoes, and chopped cilantro. Stir everything together until fully mixed. Taste and adjust the seasoning with salt and pepper as needed.
Gently spoon the quinoa mixture into each prepared bell pepper, packing it in lightly for an even fill. If you wish to add cheese, sprinkle it generously on top of the stuffed peppers.
Cover the baking dish tightly with aluminum foil and place it in the preheated oven. Bake for 25 minutes, then remove the foil and continue baking for an additional 10 minutes, or until the peppers are tender and any cheese is melted and bubbly.
Once baked, carefully remove the baking dish from the oven and allow it to cool for a few minutes. Before serving, garnish each pepper with slices of avocado and a sprinkle of additional chopped cilantro for a fresh finish.
Notes
Feel free to customize the toppings and spices to your liking.