Heat the butter and oil in a large frying pan. Add the leeks and gently cook for 5 minutes until softened but not coloured. Add the garlic and thyme, and cook for a further 2 minutes.
Add the quinoa and stir well so it is coated in the oil. Add the wine and bubble off rapidly. Keep the stock in a separate medium pan on a gentle simmer. Add a little of the stock to the frying pan, a ladle or two at a time and simmer and stir until almost all of it has been absorbed.
Continue to add the stock and stir, for 20-25 minutes. Add the peas and remaining stock and simmer for another 5 minutes until the quinoa is tender. Season to taste, stir in the parsley, lemon juice and serve in a bowl scattered with the parmesan.