Cut the tops off of the bell peppers and remove the seeds and white membranes. Place the peppers in a baking dish and set aside.
Heat the olive oil in a skillet over medium heat. Add the onion and garlic and sauté until fragrant and the onion is starting to soften, about 5 minutes.
Add the cumin, chili powder, paprika, oregano, and salt and stir to combine. Add the black beans, corn, and quinoa and cook for an additional 5 minutes.
Fill the bell peppers with the vegetable mixture and top with the grated cheese. Bake in the preheated oven until the cheese is melted and bubbly, about 20 minutes.
Garnish with diced avocado before serving.
Interesting Facts
Bell peppers are a great source of Vitamin C, Vitamin A, and Vitamin B6.
Quinoa is a complete protein, meaning it contains all nine essential amino acids.
Black beans are an excellent source of fiber and plant-based protein.