Preheat oven to 350°F/180 C.
Put quinoa and 2 cups water into a medium pot and bring to a boil.
Reduce to medium-low; cover and simmer until liquid is gone and quinoa is tender, about 15 minutes.
Let rest 5 minutes; fluff with a fork and transfer to a large bowl.
Mix in all chopped vegetables, herbs and beans.
Stuff peppers with mixture, sprinkle with feta cheese, arrange in a baking dish, drizzle olive oil and roast for 20- 30 minutes.
You can always add more chopped vegetables, courgette, or use green peas or broad beans if you cannot find edamame beans.