For the soup, in a large pot set on medium heat, heat the olive oil, then add the chopped leek and green onions. Lightly salt them, then sweat them, turning the heat down to medium low.
When the leeks have softened, and before they start to brown, add the orzo pasta. If your green beans are as thick as a pencil, or frozen, add them now with the pasta. Stir orzo and green beans through the leek mixture, then add 4 cups of stock, stirring continuously for 1 minute to avoid it sticking.
Bring to a boil, continuing to stir every minute or so, to avoid the pasta sticking to the bottom of the pot. If using home made and unsalted stock, add about ¼ tsp fine sea salt. When boiling, turn the heat down and simmer for 3 minutes, or until the green beans are cooked al dente.
Add the peas and zucchini (and the green beans, if you were using slim, French ones, and didn’t add them before), and cook for another 3 minutes, until all the veggies and the orzo are completely cooked. Add the white beans and heat through. Season the soup with additional salt, if needed, and freshly ground black pepper. Don’t be too generous with the salt, as the herb sauce will be salty as well. Take off the heat and set aside while preparing the herb sauce.
For the herb, lemon and olive oil sauce: add all ingredients to a small bowl, and stir. Start with 1 tablespoon of lemon juice. The sauce should taste very bright, and fairly salty. To serve, ladle hot soup into bowls and add about 1 tbsp of herb sauce to each plate. If desired, garnish with finely grated Pecorino cheese. For children, keep the herb sauce on the side, so they can add it or not, as they prefer.
