Stuff the cavity of the chicken with the whole lemon, whole peeled onion and bay leaf. Rub the skin with some butter and a little olive oil. Season and roast about 1 ½ hours at 180C FAN/200C/Gas Mark 6 until cooked right through. Keep the roasting tray and juices to one side to be used later on.
For the soup. Gently fry the red onion and the garlic in a large saucepan big enough to fit the whole chicken and liquid in
Add the leeks
Put in the whole cooked chicken once it is roasted – remove the lemon from the cavity before you do this
Add 2 litres of stock – and make sure that the chicken is almost completely covered
Add the roughly chopped carrots and celery sticks
Add several bay leaves, the small bunch of parsley and a lug of white wine
Leave the soup to cook for around 4 hours – check the liquid doesn’t evaporate too much and if necessary add a little water.
When the soup is cooked. First toss the sourdough chunks in the original roasting pan from the chicken and place it back in the oven for around 15 minutes at 180C fan/200C/Gas mark 6 while you are finishing off the soup.
Heat a little oil in another large pan, gently fry and soften the remaining sticks of chopped celery, the carrot and the leek
Remove the chicken from the pan and strain the soup from into the softened vegetables
Add the fresh peas and allow to cook for a minute.
Shred some of the chicken meat (enough for as many portions as you need)
Serve the soup with the meat, tarragon, parsley and freshly grated parmesan – with the roasted pieces of sourdough bread on the side