In a medium sized skillet, cook the onion and garlic for 10 minutes on medium heat. Add the spinach and frozen corn and cook for another 5 minutes. Remove from heat and add this mixture to the quinoa and mix together with a spoon. Add the tomato paste, flour, and feta cheese and continue to mix until fully blended. Add the salt and pepper.
Form “burger” patties with the mixture and set on a plate. Cover with foil and place in the refrigerator for at least 2 hours.
Remove from the refrigerator and pan fry patties in vegetable oil over medium-heat, until they are browned on each side. Serve on buns with your choice of garnishes!