Ingredients
2-3 large leeks
2 eating apples, peeled, cored
4 garlic cloves, peeled but left whole
few sprigs each of thyme, sage and rosemary
olive oil
12 good quality thick pork sausages
flaked sea salt and freshly ground black pepper
500ml/17fl oz cider
400ml/14fl oz tinned beef consommé or fresh beef stock
For the mashed potatoes:
8 medium to large floury potatoes, such as Maris Piper, King Edward or Desiree
olive oil
flaked sea salt and freshly ground black pepper
salted butter
small handful of roughly chopped fresh herbs of your choice (e.g. parsley, basil, thyme or sage) or 1-2 tsp mustard (optional)

Method
1. Preheat the oven to 200C/400F/Gas 6.
2. Stab the potatoes several times with a fork and sit on a very large piece of aluminium foil. Pour over some olive oil and add plenty of salt. Wrap the foil loosely around the potatoes and fold over the edges to seal. Place in the oven and bake for 1¾ hours. Rather than baking, they will steam in the foil, giving a fluffy centre and soft skin.
3. While the potatoes are cooking, slice the leeks fairly thinly and wash well, getting rid of any grit. Scatter into a roasting tray with the apples, garlic and herbs. Pour over some olive oil and place the sausages on top. Season the whole lot with salt and pepper, then place in the oven for about 45 minutes, turning the sausages occasionally and moving the leeks around to prevent them from sticking. If they seem to be catching in the base of the pan, add a drop of the cider.
4. To check the potatoes are cooked, carefully open the foil and insert a sharp knife into a potato. If it comes out easily, they're done. If they still seem a little hard, put them back and check again after a further 10 minutes. Once they are cooked, remove them from the oven and keep warm in the foil for about 5 minutes, then tip into a large bowl. (For some, the best part of a potato is the skin, with its lovely nutty flavour. If you'd rather, you can easily peel it away before smashing the potatoes.) Roughly smash with a potato masher, adding plenty of butter (olive oil can be used as an alternative), herbs or mustard, if using, and seasoning, resulting in a very rustic-looking fluffy mash.
5. Take the roasting tray from the oven and place the sausages on serving plates with the potatoes and keep warm.
6. Remove the herb sprigs from the roasting tray and place the tray over a high heat. Add the cider and bring to the boil. When the cider has reduced by half, add the beef consommi or stock. Bring to the boil and cook for a few minutes until the quantity of gravy has reduced by about a third, giving you a rich, full-flavoured, loose gravy. Taste and add seasoning if it's needed. Spoon the gravy and leeks over the bangers and mash and tuck in.

Alternatively, use 3 large sliced onions instead of the leeks, cooking them in exactly the same way.