Prepare the Quinoa: In a medium saucepan, bring the vegetable broth to a boil. Add the rinsed quinoa, reduce the heat to low, cover, and simmer for about 15 minutes, or until the quinoa is fluffy. Remove from heat and set aside.
Mix the Filling: In the skillet with the onions and garlic, add the black beans, corn, diced tomatoes, cooked quinoa, cumin, smoked paprika, and chili powder. Stir to combine and cook over medium heat for another 5 minutes. Season with salt and pepper to taste. Remove from heat and fold in half of the grated cheese.
Prepare the Peppers: Preheat the oven to 375. Cut the tops off the red bell peppers and remove the seeds and membranes. Place the peppers upright in a baking dish.
Stuff the Peppers: Generously spoon the quinoa filling into each bell pepper, packing it tightly. Top with the remaining grated cheese.
Bake the Stuffed Hearts: Cover the baking dish with aluminum foil and bake in the preheated oven for 25 minutes. Remove the foil and bake for an additional 10 minutes, or until the peppers are tender and the cheese is bubbly and slightly golden.
Serve: Remove from the oven and let cool slightly. Garnish with fresh cilantro or parsley and serve with lime wedges on the side for a zesty kick.