Place the duck, breast side up, in a roasting tin. Insert the sprigs of thyme into the cavity of the duck and season with salt and pepper. Sprinkle salt over the skin of the duck, then roast in the oven for 45 minutes.
Meanwhile, mix the honey and chopped thyme together in a small bowl. After the duck has been roasting for 45 minutes, remove from the oven and spread the honey mixture over the skin. Return to the oven and cook for about another 45 minutes or until the duck is cooked to your liking.
While the duck is cooking, prepare the red cabbage. Remove any damaged outer leaves, then cut the cabbage into quarters, cut away the core and slice the leaves finely across the grain. Put the vinegar into a casserole dish or stainless-steel saucepan and add 120ml (4fl oz) of water and 1 level teaspoon of salt. Tip in the cabbage and bring to the boil.
Meanwhile, peel and core the apples and cut into quarters (don’t be tempted to cut them smaller). Lay these on top of the cabbage and bring back up to the boil, then reduce the heat to low, cover with a lid and cook gently for 30–50 minutes or until the cabbage is tender. Do not overcook or the colour and flavour will be ruined. Taste for seasoning, adding more sugar if necessary, and keep warm in the pan until the duck is ready.
When the duck is cooked, remove from the roasting tin, cover with foil and place somewhere warm (such as in the oven with the heat switched off) to rest for at least 15 minutes while you make the gravy.
Place the flour and butter in a saucepan on a medium heat. Cook, stirring frequently, for about 2 minutes to make a roux, then set aside.
Place the roasting tin on a medium heat and deglaze with a little of the stock, stirring with a wooden spoon and scraping any sticky bits from the bottom of the tin. Drain off the fat using a separating jug or, if you don’t have one, pour the liquid into?a bowl and add a handful of ice cubes. After a few minutes the fat will float to the surface. Remove and discard the fat, then pour the remaining liquid into a saucepan with the remaining chicken or duck stock and place on a medium heat.
Bring the stock to the boil, whisk in the roux a little at a time and continue to boil for 2–3 minutes to thicken very slightly. Season to taste with salt and pepper. Just before serving the duck, strain the gravy through a fine sieve into a gravy boat or jug and tip the cooked red cabbage into a warmed serving dish. Carve the duck and serve immediately.