1Preheat oven to 400°F. Arrange bell pepper halves cut-side up on a baking sheet, drizzle with a little vegetable oil, and roast for 10 minutes to soften.
2While peppers roast, rinse quinoa under cold water. In a pot, bring vegetable broth to a boil, add quinoa, reduce heat to low, cover, and simmer for 15 minutes. Remove from heat and let stand 5 minutes, then fluff with a fork.
3Heat a skillet over medium heat. Sauté diced onion until softened, about 3 minutes. Add minced garlic and cook 1 minute more. Stir in cumin and smoked paprika and cook until fragrant, about 30 seconds.
4Add cooked quinoa, black beans, corn, lime zest, and lime juice to the skillet. Toss gently to combine. Season with salt and pepper to taste. Fold in cilantro.
5Remove peppers from oven. Spoon quinoa filling evenly into each pepper half. Top each with cheddar cheese.
6Return to oven and bake for 15 minutes until peppers are tender and cheese is melted and lightly golden.