Place the chicken in a freezer bag then add the flour and a few pinches of salt. Shake the bag well, making sure that the chicken pieces are evenly coated.
Cut the leeks, carrots and parsnips into 3cm thick chunks.
Heat 1 Tbsp of oil in a heavy-based pan, then sear he chicken pieces for about 5 minutes, until golden, then transfer them to a plate.
Add the leek and cook for about 5 minutes until soft, then add the carrots and turnips.
Meanwhile, peel and core the apples, then chop them into large chunks.
Add the apple and tarragon to the pan, then pour in the cider and the stock. Bring to the boil, then simmer, under cover, for about 45 minutes, until you get a thick stew.
Serve it with chopped tarragon sprinkled over it.