Toss the chicken in the seasoned flour and shake off any excess. Heat the olive oil in a large pan, add the chicken and onion and cook over a high heat for 3-4 minutes until the chicken is lightly browned. Stir in the carrots, celery and mushrooms and cook for a further 2 minutes.
Add the chicken stock, red wine and mixed herbs. Bring to the boil, cover and simmer gently for 5 minutes.
Meanwhile, stir together the self-raising flour, suet, parsley and seasoning, then add four to five tablespoons of water to make a soft dough. Shape the dough into 12 even-sized balls and drop them into the pan, taking care to space them a little apart from each other as they will swell during cooking.
Cover the pot and simmer the stew gently for a further 15-20 minutes until the dumplings are risen and cooked through. Ladle the stew into bowls and serve.