Rinse the poussin and put it in a large pot. Add about 1 litre of water - it should cover the bird well. Peel the onion and garlic, add these to the water (as whole). Heat it up, and when the soup is about to boil, using a mesh sieve, skim off the scum that accumulates on the surface (keep the liquid at a gentle simmer!).
Meanwhile peel the root vegetables - don't chop them up! If the potato is organic - you don’t need to peel it.
When the surface of the soup is scum-free, add the root vegetables and the mushrooms and bring to the boil.
Turn down the heat, put a lid on and gently cook for 30-45 minutes, until the vegetables are tender. Now add the broccoli, beans and the parsley (tied together). Turn up the heat and cook for another 5 minutes.
Add the green peas and kale and cook for another 5 minutes.
Remove the herbs and the onion before serving and cut the vegetable into bite-sized chunks.