Heat up some olive oil in a pan on a low/medium heat. Add diced onion and garlic and cook for 5-8 minutes. Add leeks, the dark green part first, then the whiter ones.
In the meantime in a blender add cooked spinach, basil, nutritional yeast, olive oil, lemon juice, salt and pepper and some water if necessary.
Add peas to the pan, the orzo pasta, enough vegetable stock to cover the orzo and miso paste. Let it cook for 2 minutes less than the package says, stir in the spinach sauce and continue cooking until it’s ready.
Serve and season with some more olive oil and walnuts.