Place the stock and chicken in a large saucepan and bring to the boil. Cover and simmer for 10 minutes then add the carrots and potatoes. Simmer for further 10 minutes until vegetables are almost cooked.

Add the lettuce, peas and salad onions. Cover and cook for 4-5 minutes until the peas are tender and the chicken is cooked through. Stir through the creme fraiche and parsley. Ladle into soup bowls and serve.