Maintain a simmer for 20 minutes, until the orzo is cooked through, the veggies are tender, and most of the liquid has been absorbed by the orzo. Stir gently, pulling at everything settling at the bottom of the pot, so that you can avoid it scorching.
Just before serving scatter in the remaining salt, pepper and parmesan cheese and stir through. If you find that it is a little thicker than you would like, add a little more stock and stir it through till warm.
Any leftovers can be stored in a sealed container in the fridge. To reheat, add what you want to a sauce pan, along with 1/4 or more stock to help loosen up the orzo. Reheat over medium low.
I state that it serves 6. But you may actually get enough to feed 8!