To cook the duck, preheat the oven to 180C.
Prick the skin of the bird all over, concentrating on the fattiest parts, but be careful not to pierce into the flesh.
Season the bird well with sea salt and pepper, including the internal cavity. Smother the bird including the cavity with butter and scatter in some herbs.
Place the bird into a good sized roasting dish. Place the bird in the oven and cook for 30 minutes per kg. You can check to see if your bird is cooked by inserting a metal skewer into the join between the leg and the breast, if the juices run light pink-clear this is a good indication your duck is done. Rest for 30 minutes, while you make the risotto.
In the mean time, in a heavy based saucepan, melt a little bit of butter, and then add into the pan the chopped onion, chopped garlic and chopped thyme. Sauté until the onion is translucent. Add the mushrooms and the pearl barley and continue to sauté for a couple more minutes. Add the stock gradually, stirring the pearl barley continuously until all the stock has been used and the pearl barley is soft with a slight bite (al dente).
To the risotto, add the remaining butter, cheese, mustard and lemon juice. Season well and continue stirring.
Serve in deep bowls with the carved duck strewn over the top.
A forest feast for the senses and one that will remain in your autumn repertoire.