Preheat the Oven: Preheat your oven to 375°F (190°C).
Prepare the Bell Peppers: Cut the tops off the bell peppers and remove the seeds and membranes. If needed, trim the bottoms slightly so they stand upright. Arrange the peppers in a baking dish.
Cook the Filling: In a large skillet, heat the olive oil over medium-high heat. Add the diced onion and cook until softened, about 3-4 minutes. Add the minced garlic and cook for another minute until fragrant. Add the diced zucchini and cook for another 5 minutes until tender.
Add the Remaining Ingredients: Stir in the corn, black beans, diced tomatoes, cooked quinoa or brown rice, chili powder, cumin, paprika, oregano, salt, and pepper. Mix well and cook for another 2-3 minutes until everything is heated through and well combined.
Stuff the Peppers: Spoon the vegetable mixture into the bell peppers, packing it down slightly. Top each pepper with a generous amount of shredded cheese.
Bake the Peppers: Cover the baking dish with aluminum foil and bake in the preheated oven for 30 minutes. Remove the foil and bake for an additional 10-15 minutes, or until the cheese is melted and bubbly and the peppers are tender.
Garnish and Serve: Remove the stuffed peppers from the oven and let them cool for a few minutes. Garnish with chopped fresh cilantro or parsley and serve with lime wedges on the side.