In a large skillet saucepan, add oil, turn to medium-low heat, add white mushrooms and saute for about 3 minutes. Add onion, garlic and celery to mushrooms and continue cooking until onion and celery are tender, about 4 minutes.
Add Quinoa, red pepper flakes, black pepper and salt to taste, stir to combine. Add vegetable stock, stir and cook for 15 minutes or until liquid is absorbed.