Preheat oven to 400 degrees. Bring vegetable stock (or broth) and a pinch of salt to a boil in a small pot. Once boiling, add quinoa. Cover and cook on low heat for 15-20 minutes. Alternatively, you can cook it in the Instant Pot (see notes).
Arrange the pepper halves on a baking sheet and drizzle with 1 TBSP olive oil. Sprinkle with salt and pepper. Bake until softened , about 15 minutes.
Meanwhile, heat the remaining 1 TBSP olive oil in a large skillet over medium-high heat. Add onions, green onions and garlic, cook for 4-5 minutes, until softened. Stir in the ground beef, chili powder, cumin, paprika and cayenne and cook, breaking up with a spoon, until the meat is browned and cooked.
Add in beans and tomatoes and let simmer for 5 minutes. Stir in cooked quinoa and season with salt and pepper, to taste.
Fill peppers with quinoa mixture and sprinkle with cheese. Bake 15 minutes. Serve with lime wedges on the side.
Video
Notes
Have an Instant Pot? Try cooking your quinoa in there! It's my favorite way to cook quinoa now. Find the simple instructions here.