Roast the chicken in your normal way.
For this recipe I just rub with a little olive oil, season and bung it in a 220℃/200℃ fan oven for 20 minutes, turn the heat down to 180℃/160℃ fan, pop in half a glass of white wine, and roast for about another hour or until the juices in the thigh run clear or it registers 75℃ on the meat thermometer.
While the chicken is roasting, prepare your veg by chopping the onion and celery, and dice the carrots and potatoes to a similar size.
Heat the olive oil in a large saucepan and saute the vegetables for 5-10 minutes with colouring too much.
Add the stock and the bouquet garni and simmer on a medium heat for about 30 - 35 minutes or until the carrots and potatoes are tender. (if you have a pressure cooker, this can be done in 5 minutes).
Taste for seasoning and only add if you think you need to.
Decide how you like your soup, and to thicken whizz half of it with a stick blender, and if it is now too thick, just loosen with a little stock.
If you prefer a smooth soup, just blend all of it before adding the roast chicken and peas.
Shred or chop meat from the chicken (as much or little as you fancy) from the thighs and legs, not forgetting the ‘oysters’, the two bits of dark meat shaped like little oysters, near the backbone/thighs of the bird. They aren’t very big, but are the tastiest morsels you can imagine. In fact if you remember about them, they might not even reach the soup!
You can also scrape off any bits of caramelised chicken that have stuck to the bottom of the roasting tin, and add that to the soup. These have fantastic intense chicken flavour and will only enhance the soup.
Throw in a good handful of peas and heat through until the peas are done and all the chicken and its chickeny-ness are well stirred in.
Great with some crusty bread for a hearty lunch, or in a flask on the side of a windswept hill.