Preheat the oven to 450 degrees F.
Bring the quinoa and stock to a boil. Cover and simmer until the liquid is absorbed and the grain looks translucent, 12 to 15 minutes. Then fluff with a fork. You will have about 4 cups of cooked grain.
Drizzle the bell pepper halves with olive oil and season both sides with salt and pepper. Roast cut-side down until the peppers are just tender, about 20 minutes. Remove from the oven. Place in a baking dish cut side up.
Meanwhile, heat 2 tablespoons olive oil, over medium-high heat. Add the garlic, carrots, onions and banana peppers, and season with salt and pepper. Cook partially covered to tender, 10 to 12 minutes. Add the herbs and tomatoes, and combine with the quinoa.
Fill the pepper halves with the quinoa and vegetable filand drizzle with olive oil. Bake at 375 degree about 15-20 minutes or until the peppers are hot through.