Boil your quinoa according to package directions. I added one cup of quinoa and 3 cups of water, and I got about 3 cups of cooked quinoa. Set aside to cool.
Preheat oven to 400 degrees F. Prepare a baking sheet (make sure it's small to hold 6 stuffed peppers standing up) and spray with non-stick cooking spray, or olive oil.
Cut the tops of the peppers. Remove the seeds from inside the peppers and stand them up in baking dish. Set aside.
Heat some olive oil in a non-stick frying pan and add the onion and all spices. Cook for a couple minutes or until the onion is fragrant but not brown.
Add the canned red kidney beans, and the corn. Stir and cook for another 2 minutes. Then, add the cooked quinoa and cook for a few minutes.
In the end add your tomato puree and stir well. Cook for 3-4 minutes. Remove from heat.
Stuff your peppers with the quinoa mixture up to the top. Sprinkle some feta cheese on top.
Bake them with a baking aluminium foil on top for about 25 minutes. Remove the foil and cook for another 5-10 minutes or until the Feta is cooked and lightly brown.
Serve hot and enjoy!