Heat the oil in a large pan over a medium heat and fry the leek with a pinch of salt for 6 minutes, then add the mushrooms and fry for 6-7 minutes until soft. Add the garlic and stir for a minute, then transfer a quarter of the veg to a plate and keep warm. Stir the quinoa into the pan and cook for a minute.
Turn up the heat, add the white wine and let it bubble for 2 minutes. Add the stock in three stages, adding more when the previous addition has been absorbed. Cook for 15-20 minutes, stirring occasionally. The quinoa should still have some bite to it.
Once the quinoa is cooked, season it and stir in the lemon zest and cheese. Top with the crispy onions, the reserved vegetables and parsley (if using). Serve with lemon wedges to squeeze over.
