Slow cooked lamb shoulder ( 12 hours )

Ingredients 1.6kg lamb shoulder Big onions ( skin left on and sliced into thick chunks ) Few celery sticks roughly chopped 500ml water For the marinade 4 stalks of rosemary ( leaves finely chopped ) 2 cloves of garlic ( finely chopped ) 1 tbsp oregano Salt Pepper 65ml of extra virgin olive oil For the jus Tsp cornflour 65ml water Salt Pepper Extra Grease proof paper Tin foil Mix the marinade together and rub onto the lamb Let it marinade for a minimum of 2 hours max 24 hours After the lamb has marinated cook in the oven at 200c for 45 minutes After 45 minutes take the lamb out of the oven and reduce the temperature to 100c Wrap the lamb in grease proof paper and cover tin with tinfoil tightly return to the oven for 12 hours