Steam the green beans until just tender and set aside.
Place the lemon juice and Dijon mustard in a large bowl. Whisk in the olive oil and season with salt and freshly ground black pepper. Use a vegetable peeler to slice each zucchini into long thin strips, dropping them into the bowl of vinaigrette as you go. Carefully mix in the green beans then sprinkle over the mint and sweet marjoram leaves.
Place in a serving bowl and top with thin slices of Puhoi Valley Cow’s Milk Feta.
Serve with lemon for squeezing if wished and extra black pepper.